WORKS OF PROF. HEINRICH RIES PUBLISHED BY JOHN WILEY & SONS Building: Stones and Clay Products A Handbook for Architects. 8vo, xiii+415 pages, 59 plates, including full-page half-tones and maps, 20 figures in the text. Cloth, $3.00 net Clays: Their Occurrence, Properties and Uses With Especial Reference to Those of the United States. Second Edition, Revised. 8vo, xix + 554 pages, 112 figures, 44 plates. Cloth, $5.00 net. By RIES AND LEIGHTON History of the Clay-working: Industry in the United States By Prof. Heinrich Ries and Henry Leighton, Assistant Economic Geologist, New York Geo- logical Survey. 8vo, viii + 270 pages, illustrated. Cloth, $2.50 net. PUBLISHED BY THE MACMILLAN CO. Economic Geology, with special reference to the United States. 8vo, xxxii + 589 pages, 237 figures, 56 plates. $3.50 net. BUILDING STONES AND CLAY-PRODUCTS A HANDBOOK FOR ARCHITECTS BY HEINRICH RIES, PH.D. \ I Professor of Economic Geology in Cornell University; Fellow, Geological Society of America; Member, American Institute of Mining Engineers, Canadian Mining Institute, American Society for Testing Materials, American Ceramic Society, English Ceramic Society FIRST EDITION FIRST THOUSAND NEW YORK JOHN WILEY & SONS LONDON: CHAPMAN & HALL, LIMITED 1912 COPYRIGHT, 1912, BY HEINRICH RIES Stanbopc ]press F. H.GILSON COMPANY BOSTON, U.S.A. PREFACE THAT at least an elementary knowledge of the subject of build- ing stones and clay products is of importance to the architect few people will deny, since familiarity with their properties, durability, and, in the case of clay products, their methods of manufacture will enable him to select and use these materials more intelligently. At the same time, the preparation of an elementary work on the subject is not free from difficulties, for the reason that most architects have but a limited knowledge of geology and ceramic technology. The author has, therefore, attempted to state facts and explanations as simply as possible, and as a further aid in this direction has included a glossary at the end of the book. The general arrangement of the book follows the course of lectures given each year to the students in the College of Archi- tecture of Cornell University, and it has been the encouraging reception which these received that has led the author to give them to the public. The work is not intended as an exhaustive treatise, but, in stead, aims to give simply the fundamentally important facts. It is therefore, beyond the scope of the book to take up any but the more important occurrences of building stone, and those who desire detailed information on this point will consult our standard American work, " Stones for Building and Decora- tion " by G. P. Merrill. Since the architect often desires to know how extensively and for what purposes the different building stones have been used, an attempt has been made to give a list of structures in which the more important ones at least have been placed. The author wishes to acknowledge here assistance and advice received from many persons in the preparation of the work iii 263614 IV PREFACE including Mr. E. C. Stover, Trenton Potteries Co., Trenton, N. J. ; Mr. W. H. Gorsline, Rochester, N. Y.; Prof. C. W. Parmalee, Rutgers College, New Brunswick, N. J. Acknowledgments for cuts or photos loaned are made under the respective illustrations. HEINRICH RIES. CORNELL UNIVERSITY, ITHACA, N. Y. June, 1912. CONTENTS. PAGE PREFACE iii CONTENTS v LIST OF PLATES , jd LIST OF FIGURES xv INDEX 401 PART I. BUILDING STONES. CHAPTER I. ROCK MINERALS AND ROCKS 3 Introduction, 3; Rock-forming minerals, 5; Physical properties, 5; Hardness, 6; Cleavage, 6; Lustre, 6; Form, 6; Quartz, 7; Feldspars, 7; Orthoclase, 7; Plagioclase feldspar, 7; Micas, 8; Amphibole, 9; Horn- blende, 9; Tremolite, 9; Pyroxene, 9; Calcite, 10; Aragonite, 10; Dolomite, 10; Gypsum, 10; Serpentine, n; Talc or steatite, n; Olivine, n; Garnet, n; Chlorite, n; Pyrite or iron pyrite, 12; Mag- netite, 12; Limonite, 12; Rocks, 12; Igneous rocks, 12; Granite, 18; Pegmatite, 18; Syenite, 23; Diorite, 23; Gabbro, 23; Peridotite, 23; Pyroxenite, 23; Granite porphyry, 23; Syenite porphyry, 23; Diorite porphyry, 24; Felsite, 24; Basalt, 24; Stratified rocks, 24; Sandstone, 29; Conglomerate, 29; Shale, 29; Limestone, 29; Chalk, 30; Calcareous tufa, 30; Travertine, 30; Onyx, 30; Coquina, 30; Dolomite, 30; Meta- morphic rocks, 30; Quartzite, 30; Slate, 30; Phyllite, 31; Marble, 31; Ophicalcite, 31; Gneiss, 31; Schist, 31; Structural features affecting quarrying, 31; Bedding, 32; Joints, 32. CHAPTER II. PROPERTIES OF BUILDING STONE 36 Texture, 36; Hardness, 36; Color, 37; Variation in color, 38; Change of color, 38; Polish, 40; Specific gravity and porosity, 40; Absorption, 44; Quarry water, 44; Crushing strength, 44; Transverse strength, 51; Frost resistance, 54; Fire resistance, 55; Expansion and contraction of building stones, 69; Abrasive resistance, 70; Discoloration, 73; Effect of sulphurous acid gas and dilute sulphuric acid, 74; Effect of carbonic acid gas, 74; Chemical composition of building stones, 75; Weathering and decay of building stones, 75; Disintegration, 76; Temperature VI CONTENTS PAGE changes, or heat and cold, 76; Expansion caused by freezing, 79; Abra- sive action, 80; Plant action, 80; Careless methods of extraction and working, 80; Decomposition, 81; Sulphurous and sulphuric acids, 85; Hardening of stone on exposure, 85; Life of a building stone, 86; Sap, 87; Literature on building stones, 87; General works, 87; Serials, 88; Special papers, 88. CHAPTER III. IGNEOUS ROCKS (CHIEFLY GRANITES) AND GNEISSES 93 Characteristics of granites, 94; Elasticity, 94; Flexibility, 94; Expan- sibility, 95; Porosity, 95; Fire resistance, 95; Chemical composition, 95; Classification, 95; Structure of granites, 96; Sheets or beds, 96; Knots, 96; Inclusions, 99; Dikes, 99; Black granites, 99; Tests of granite, 99; Uses of granite, 105 ; Distribution of igneous rocks (chiefly granites) and gneisses in the United States, 105; Eastern belt, 105; Maine, 106; North Jay, 106; Crotch Island, 106; Hallowell, 106; Vinalhaven and Hurri- cane Islands, 109; Red Beach, 109; Addison, 109; Jonesboro, no; Blue Hill, no; Brookville, no; Dix Island, no; Clark's Island, no; Machias, no; Pleasant River, no; Stonington, no; Classification of Maine granites, no; New Hampshire, in; Concord, in; Milford, 112; Conway, 112; Auburn, 112; Troy, 112; Fitzwilliam, 112; Mascoma granite, near Enfield, 113; Classification of New Hampshire granites, 113; Vermont, 116; Hardwick, 116; Barre, 116; Bethel, 116; Wood- bury, 119; Windsor, 119; Massachusetts, 120; Milford, 120; Rock- port, 120; Chester, 125; Quincy, 125; Classification of Massachusetts granites, 125; Rhode Island, 128; Westerly, 128; Connecticut, 128; Branfprd township, 131; Greenwich, 131; Waterford township, 131; Millstone, 131; Groton, 132; Market price of granites, 136; New York, 137; New Jersey, 137; Pomp ton pink granite, 138; Dover light gray granite gneiss, 138; Cranberry Lake white granite gneiss, 138; German Valley gray granite, 138; Trap rock, 138; Maryland, 138; Granites, 141; Port Deposit, 141; Ellicott City, 141; Guilford, 141; Woodstock, 141; Frenchtown area, 142; Gneisses, 142; Virginia, 142; Petersburg area, 142; Richmond area, 142; Fredericksburg area, 145; Other localities, 145; North Carolina, 145; Even granular granites, 146; Coastal plain, 146; Piedmont plateau region, 146; Greystone, 149; Raleigh, 149; Wise, 149; Rowan County, 149; Mount Airy, 149; Porphyritic granites, 149; Miscellaneous rocks, 150; South Carolina, 150; Heath Springs, 153; Columbia, 153; Georgia, 154; Elberton-Ogelsby-Lexington area, 154; Lithonia-Conyers-Lawrenceville area, 154; Fairburn-Newman-Green- ville area, 154; Stone Mountain area, 155; Sparta area, 155; Alabama, 155; Wisconsin-Minnesota area, 155; Wisconsin, 155; Montello, 155; Berlin, 156; Warren, 156; Waupaca, 156; Wausau, 157; Amberg, 157; Minnesota, 157; Southwestern area, 158; Missouri, 158; Graniteville, 158; Knob Lick, 158; Arkansas, 159; Oklahoma, 159; Wichita Moun- tains, 159; Arbuckle Mountains, 159; Texas, 160; Cordilleran area, 160; Montana, 160; Colorado, 160; California, 161; Rocklin, 161; Ray- mond, 161; Riverside County, 161; Oregon, 161. CONTENTS Vii CHAPTER IV. PAGE SANDSTONES 162 Texture, 162; Hardness, 162; Color, 163; Absorption, 163; Crushing strength, 163; Weathering qualities, 165; Fire resistance, 165; Varieties of sandstone, 165; Arkose, 165; Bluestone, 165; Brownstone, 165; Cal- careous sandstone, 165; Ferruginous sandstone, 166; Flagstone, 166; Freestone, 166; Graywacke, 166; Quartzite, 166; Distribution of sand- stones and quartzites, 166; New England States, 166; Eastern Atlantic States, 167; New York, 167; Medina sandstone, 167; Potsdam sand- stone, 167; Warsaw blue stone, 168; Hudson River bluestone, 168; New Jersey, 168; Pennsylvania, 169; Maryland, 169; Virginia, 170; West Virginia, 170; Alabama, 170; Central States, 170; Ohio, 170; In- diana, 173; Illinois, 174; Michigan, 174; Wisconsin, 174; Minnesota, 175; Missouri, 176; Arkansas, 176; Western States, 176; Montana, 176; Colorado, 176; Washington, 177; California, 177. CHAPTER V. LIMESTONES AND MARBLES 178 Limestones and dolomites, 178; Color, 178; Hardness, 178; Texture, 178; Absorption, 181; Weathering qualities, 181; Crushing strength, 181; Fire resistance, 181; Tests of limestone, 181; Chemical composition, 183; Varieties of limestone and dolomite, 183; Chalk, 183; Coquina, 183; Dolomite, 183; Fossiliferous limestone, 183; Hydraulic limestone, 183; Lithographic limestone, 183; Magnesian or dolomitic limestone, 184; Marble, 184; Oolitic limestone, 184; Travertine, calcareous tufa, or calc sinter, 184; Distribution of limestone in the United States, 184; New York, 189; New Jersey, 189; Pennsylvania, 189; Maryland, 190; Virginia, 190; West Virginia, 190; Alabama, 190; Florida, 191; Illinois, 191; Indiana, 191; Kentucky, 192; Ohio, 192; Wisconsin, 192; Minne- sota, 195; Missouri, 196; Iowa, 196; Kansas, 196; Texas, 197; Cor- dilleran region, 197; Marbles, 197; Mineral composition, 197; Color, 198; Texture, 198; Weathering qualities, 201; Absorption, 201; Crushing and transverse strength, 201; Uses of marbles, 201; Dis- tribution of marbles in the United States, 202; Vermont, 202; Light marbles, 207; Dark marbles, 213; Ornamental or fancy marbles, 213; Champlain marbles, 214; Massachusetts, 215; Connecticut, 215; New York, 215; Pennsylvania, 216; Maryland, 216; Virginia, 217; North Carolina, 217; Tennessee, 218; Georgia, 218; Alabama, 223; Mis- souri, 223; Colorado, 223; Arizona, 223; California, 224. CHAPTER VI. SLATE 225 Classification of slate, 225; Properties of slate, 229; Sonorousness, 229; Cleavability, 229; Cross-fracture, 229; Character of cleavage surface, 229; Lime, 229; Color and discoloration, 229; Presence of clay, 229; Presence of marcasite, 230; Strength, 230; Toughness or elasticity, 230; Density or specific gravity, 230; Abrasive resistance, 230; Corrodibility, 230; Electrical resistance, 230; Tests of slates, 233; Price of slate, 235; Quarrying, 236; Distribution of slate in the United States, 236; Maine, Viii CONTENTS PAGE 2 37> Vermont, 237; Sea green slate, 237; Unfading green slate, 237; Purple and variegated, 237; New York, 238; New Jersey, 238; Penn- sylvania, 238; Maryland, 241; West Virginia, 241-; Virginia, 241; Georgia, 241; Arkansas, 241; California, 242. CHAPTER VII. SERPENTINE 243 Distribution of serpentine in the United States, 243; Massachusetts, 244; Vermont, 244; New York, 244; New Jersey, 244; Pennsylvania, 244; Maryland, 249; Georgia, 249; California, 249; Washington, 249; Onyx marbles, 249. PART II. CLAY PRODUCTS. CHAPTER VIII. PROPERTIES OF CLAY 253 Physical properties, 253; Plasticity, 253; Shrinkage, 254; Tensile strength, 255; Fusibility, 255; Chemical properties, 256; Analyses of clay, 258. CHAPTER IX. BUILDING BRICK 259 Kinds of brick, 259; Raw materials used for building brick, 263; Common brick, 263; Pressed brick, 263; Enameled brick, 264; Methods of brick manufacture, 264; Preparation, 264; Molding, 265; Soft mud process, 265; Stiff mud process, 269; Dry press and semi-dry press process, 275; Re-pressing, 276; Drying, 276; Burning, 279; Compari- son of brick made by different processes, 283; Testing of brick, 284; Crushing test, 284; Transverse test, 294; Absorption test, 296; Rate of absorption, 300; Permeability, 301; Relation between crushing strength, transverse strength, and absorption, 302 ; Fire tests, 302; Coefficient of expansion, 305; Frost test, 305; Proposed standard specifications for building brick, 307; Selection of samples, 307; Transverse test, 307; Compression test, 308; Absorption test, 308; Freezing and thawing tests, 308; Requirements, 309; Specific gravity, 309; Efflorescence or scum on bricks, 312; Testing bricks for scumming power, 313; Requisite qualities of brick, 314; Common brick, 314; Pressed brick, 314; Enameled brick, 317. CHAPTER X. ARCHITECTURAL TERRA COTTA : 320 Definition, 320; Raw materials, 320; Method of manufacture, 320; Properties of terra cotta, 324; Testing terra cotta, 324; Terra cotta scum, 328; Fire-resisting properties, 328. CHAPTER XI. HOLLOW- WARE FOR STRUCTURAL WORK AND FIREPROOFING 333 Types of hollow-ware, 333; Raw materials and manufacture, 333; Fireproofing, 334; Furring blocks, 338; Hollow block and brick, 338; Tests of hollow blocks, 340; Fire tests, 346. CONTENTS ix CHAPTER XII. ROOFING TILE 349 Shingle tile, 349; Old Spanish, Normal, Mexican, Mission or Roman tile, 350; Modern Spanish or S tiles, 350; Interlocking tile, 351; Ma- terials and manufacture, 352; Porosity of roofing tiles, 352; Requisite characters of roofing tile, 359; Tests of roofing tile, 359; Miscellaneous clay slabs, used for roofing purposes, 360; Special shapes, 360. CHAPTER XIII. WALL AND FLOOR TILE 363 Manufacture of wall tile, 363; Properties of floor tile, 365; Method of manufacture, 366; Tests of wall tile, 369; Tests of floor tile, 369. CHAPTER XIV. SEWER PIPE AND SANITARY WARE 372 Sewer pipe, 372; Raw materials, 372; Manufacture, 372; Requisite qualities, 374; Strength, 374; Durability, 377; Serviceability, 377; Specifications, 377; Iowa standard specifications for drain tile and sewer pipe, 379; Absorption tests, 379; Bearing strength, 380; Computing the Modulus of Rupture, 381; Other proposed standard tests, 382; Miscellaneous tests, 384; Other hollow shapes, 385; Sewer blocks, 386; Sanitary ware, 388; Vitreous ware, 388; Solid porcelain, 388; Raw materials, 388; Manufacture, 388; Properties of sanitary ware, 388; Glossary, 390. LIST OF PLATES PLATE PAGE I. A small fine-grained dike of dark diabase cutting a lighter colored syenite 13 II. A volcanic rock, trachyte, showing porphyritic texture 15 III. Fig. i. Moderately fine-grained granite, Hallowell, Me 19 Fig. 2. Very coarse-grained granite, St. Cloud, Minn 19 IV. Coarse-grained somewhat porphyritic granite from Crotch Island, Me 21 V. Pegmatite, showing coarse-grained texture 25 VI. Fig. i. View in a limestone quarry showing the horizontal strati- fication planes and vertical joint planes 27 Fig. 2. General view of a limestone quarry showing stratified character of the rock 27 VII. Biotite gneiss, showing characteristic banded structure of this rock 33 VIII. Fig. i. Gray marble, Gouverneur, N. Y., showing contrast be- tween tooled and polished surfaces 41 Fig. 2. Gabbro from Keesevilte, N. Y., showing contrast between tooled and polished surfaces 41 IX. Fig. i. Photomicrograph of a section of granite 45 Fig. 2. Photomicrograph of a section of diabase 45 X. Photomicrograph of a section of quartzitic sandstone 47 XI. Fire tests on 3-in. cubes of sandstones from Pleasantdale, N. J. . 57 XII. Fire tests on 3-in. cubes of limestone, Newton, N. J 59 XIII. Fire test of 3-in. cubes of gneiss, Mt. Arlington, N. J. . 61 XIV. Fire tests of 3-in. cubes of sandstone, Warsaw, N. Y 63 XV. Fire tests of 3-in. cubes of diabase, Lambertville, N. J 65 XVI. Results of abrasion tests with sand blast 71 XVII. Fig. i. Weathering of red sandstone, Denver, Col 77 Fig. 2. Weathered sandstone, second story County Court House, Denver, Col 77 XVIII. Scum of soluble salts, which has caused surface disintegration of sandstone 83 XIX. Church in Mexico City constructed of volcanic tuff 91 XX. Fig. i. Granite quarry, Hardwick, Vt 97 Fig. 2. Granite quarry at North Jay, Me 97 XXI. Map showing distribution of igneous rocks and gneisses in the United States 102 XXII. Cleveland Trust Company, Cleveland, O., constructed of North Jay, Me., granite 107 XXIII. Map of Vermont showing granite centers and prospects 117 xi xii LIST OF PLATES PLATE PAGE XXIV. Map of Massachusetts showing quarry centers 121 XXV. Fig. i. Milford, Mass., granite showing speckled appearance, caused by biotite scales against lighter background of quartz and feldspar 1 23 Fig. 2. Battle monument on Lookout Mountain, Chattanooga, Tenn., constructed of Milford pink granite 123 XXVI. Battle monument, West Point, N. Y., polished shaft of Branford granite, 41 ft. 6 in. long and 6 ft. diameter. 129 XXVII. Map of Maryland showing distribution of granite quarries and granite and gneiss areas 137 XXVIII. Fig. i. Port deposit, Maryland, gneissic-granite with face cut at right angles to banding 143 Fig. 2. Port Deposit, Maryland, gneissic-granite with face cut parallel to the banding 143 XXIX. Fig. i. Leopardite from North Carolina 151 Fig. 2. Orbicular gabbro from North Carolina 151 XXX. U. S. Post Office, Toledo, O., constructed of Berea sandstone .... 171 XXXI. Fig. i . Limestone showing dark flint nodules 1 79 Fig. 2. Tremolite in dolomitic marble 179 XXXII. Map showing limestone areas of United States 186 XXXIII. Statue of Labor, cut in "Old Hoosier" Light Blue Bedford limestone for City Investment Building, New York City 193 XXXIV. A decorative marble showing a brecciated structure 199 XXXV. Interior of Harris County Court House, Houston, Texas, showing Creole matched marble 203 XXXVI. Fig. i. White marble, Vermont 205 Fig. 2. Gray marble, Vermont 205 XXXVII. Fig. i. Quarries in Travertine near Tivoli, Italy 209 Fig. 2. Quarry of Vermont Marble Company, Proctor, Vt 209 XXXVIII. Kimball monument, Chicago, 111., done in Vermont white marble 211 XXXIX. Monolith of Georgia marble, 27 ft. 2 in. by 4 ft. 4 in. by 4 ft. 3 in., weight 50 tons 219 XL. Slabs of Alabama marble showing variation from pure white to those which are clouded and streaked with mica 221 XLI. Fig. i. Slate quarry, Penrhyn, Pa 227 Fig. 2. Splitting slate 227 XLII. Map showing distribution of slate in the United States 239 XLIII. Serpentine pedestal, Charlottesville, Va 245 XLIV. Serpentine from Roxbury, Vt 247 XLV. Fig. i. Ornamental dry-pressed brick 261 Fig. 2. Tapestry brick 261 XL VI. Fig. i. Common red soft-mud brick 267 Fig, 2. A common soft-mud brick 267 XL VII." Section of stiff-mud brick showing laminations 271 XL VIII. ' Dry-press brick machine 273 XLIX. Fig. i. Common brick split by lime pebbles 277 Fig. 2. Repressed brick 277 LIST OF PLATES xiii PLATE PAGE L. Fig. i. Setting brick for a scove kiln 281 Fig. 2. Down-draft kilns used for burning sewer pipe 281 LI. Brickotta, a style of ornamental brickwork 315 LII. Terra cotta panel used in construction of State Education Build- ing, Albany, N. Y 321 LIII. Terra cotta panel, Rice Hotel, Houston, Tex 325 LIV. Interior of Railway Exchange Building, Chicago, 111 329 LV. Flat arch of fireproofing 335 LVI. Regular and special shapes of Spanish interlocking tile 353 LVII. Fig. i. Interlocking shingle tile showing obverse (A) and reverse (B)side 357 Fig. 2. Molding 3o-inch sewer pipe in pipe press 357 LVIII. Encaustic tile 367 LIX. Sewer pipe and fittings 375 LIST OF FIGURES FIG. PAGE 1. Sandstone broken by transverse strain caused by settling of the building 52 2. Effect of fire on granite columns, U. S. public storehouse, Baltimore. ... 55 3. Map showing granite producing areas of North Carolina 147 4. Diagram showing electric connections made in testing slate 231 5. Diagram showing some patterns of slate that can be cut on a machine .... 235 6. Diagram showing section of slate rcof with starting and finishing courses 236 7. Soft-mud brick machine 266 8. Manufacture of brick by stiff-mud process 270 9. Diagram of crushing and transverse tests made on soft-mud brick from Wisconsin 286 10. Diagram showing absorption tests on Wisconsin soft-mud brick after 48 hours' immersion ; 290 11. Diagram of crushing and transverse tests on Wisconsin stiff -mud brick . . 291 12. Diagram showing absorption tests on Wisconsin stiff-mud brick after 48 hours' immersion 292 130. Diagram of crushing and transverse tests on Wisconsin dry-pressed brick 136. Absorption tests of same series 293 14. Different styles of shingle tile 349 15. Old Spanish or Mission tiles 350 16. Section of roof showing modern Spanish tile, cresting, hip rolls and finials 351 17. Quarry tile 360 18. Finials for tile roof 361 19. Graduated tower tile. Spanish pattern 362 20. Sections of sewer blocks 386 xv PART I. BUILDING STONES. BUILDING STONES AND CLAY-PRODUCTS. CHAPTER I. ROCK MINERALS AND ROCKS. INTRODUCTION. UNDER the term Building Stones are included all those rocks which are employed for ordinary masonry construction, such as walls and foundations, for ornamentation, roofing and flagging. Many different stones are used for structural work, and, owing to the abundance of these in nearly all parts of the United States, as well as the growing demand for this class of building material, the industry has assumed proportions of considerable size. The total quantity of stone quarried annually in the United States is large, but all of it is not employed for structural work. An attempt has been made, however, to separate the value of that so used from that consumed in other industries with the following results, the figures being taken from the 1910 report on Mineral Resources, issued by the United States Geological Survey. APPROXIMATE VALUE OF BUILDING STONE PRODUCED IN 1910. Granites $10,325,874 Trap rock 87,832 Sandstone 2,272,024 Bluestone 518,660 Limestone 5,272,024 Marble 8,980,240 $27,456,654 Practically every state produces some building stone, and many quarries are operated only for local use, partly because the weight of stone prohibits long hauls unless the material is of high grade. 3 "4V BUILDING STONES AND CLAY-PRODUCTS *" c By*firf the larger part of the building stone quarried is for ordinary dimensional work and may be sold in the rough to be dressed later. This applies chiefly to granite, sandstone, limestone and trap. For ornamental work, and this calls for a considerable quantity of stone, the material has to meet varying requirements. In the first place it should lend itself to carving, and that some stones serve this purpose well is shown by the many intricate and beauti- ful designs on buildings and monuments. For monumental work, also, and decorative work, a highly polished surface is often wanted, and the granites, marbles and serpentines are usually found well adapted to this need. Inscriptional work necessitates the selection of a stone that will give good contrast between the cut and polished surface, a character found in many of the darker granites and marbles. In considering the selection of a building stone, the architect is usually guided either by cost or decorative value, the dura- bility or weather-resisting qualities of the material being some- times overlooked. The latter is a serious neglect if the stone is to be employed for exterior work in a severe climate. Most of the building stone employed for constructional work in this country is from domestic sources, and not a little decora- tive stone is also obtained here ; but large quantities of varie- gated marble for ornamental purposes, and even some other kinds of stone, are imported from foreign countries. This can hardly be due entirely to the non-existence of such materials in the United States, but rather perhaps to the reluc- tance of American quarrymen to incur the risk and expense of placing a new stone on the market in competition with the foreign ones already so widely used. The factors which may be said to influence the selection of a building stone, arranged in the order of importance apparently assigned to them by many, are cost, color, fashion and durability. The cost will naturally be a dominant factor in the selection of a stone, and depends on its location, ease of quarrying, dress- ing and beauty. ROCK MINERALS AND ROCKS 5 Color often exercises a determining influence, and this, com- bined with other considerations, sometimes starts a fashion which leads to the widespread use of certain stones. An excel- lent illustration of this was the selection, for many years, of the Connecticut brownstone in many eastern cities. More recently Indiana limestone and Ohio sandstone have met the popular fancy, and these two are now used in vast quantities. Durability is often apparently given little consideration where a stone of high decorative character is sought, although it should in every instance be a factor of primary importance. A study of the properties of building stones can hardly be taken up without some knowledge of their mineral constituents, or at least the common minerals which occur in them, because these are used for purposes of identification and individually influence the different properties of the stone to a marked degree. The number of important or essential minerals in building stones are comparatively few, but in addition to these there are many of subordinate rank, often in such small grains as to be scarcely visible to the naked eye. Their presence may be of scientific interest, but the majority of them, except when present in large amount (and this is rare), exert but little influence on the character of the rock. ROCK-FORMING MINERALS. 1 A mineral may be defined as a natural inorganic substance of definite chemical composition occurring in nature. There are a great many known mineral species, but only a very small number are important constituents of building stones. Not a few others are present in very small amounts, scattered grains, sometimes of microscopic size. These in many cases have little or no effect on the quality of the stone. Physical Properties. In the determination of minerals, cer- tain physical characters, such as the cleavage, hardness, lustre and crystal form, are commonly made use of, and in the study 1 Those desiring to read up the subject of rock-forming minerals in more de- tail are referred to Dana, " Minerals and How to Study Them " (Wiley & Sons); also Hatch, "Mineralogy" (Whittaker and Co.). 6 BUILDING STONES AND CLAY-PRODUCTS of rocks, by means of thin sections examined under the micro- scope, the optical properties of the minerals are of great diag- nostic importance. The more important physical properties may now be denned. Hardness. The different mineral species usually show a definite degree of hardness, and this property can be expressed numerically, with reference to a graded scale of 10 minerals, ranging from those which are very soft to the hardest ones known. This scale is as follows: 1. Talc. 6. Orthoclase. 2. Gypsum. 7. Quartz. 3. Calcite. 8. Topaz. 4. Fluorite. 9. Sapphire. 5. Apatite. 10. Diamond. Any member of the series will scratch any of the others below it. Talc is readily scratched by the finger nail, and gypsum with difficulty. A good steel blade will barely scratch orthoclase, and quartz is sufficiently hard to scratch glass. The hardness of any other mineral can be determined by testing it with those of the hardness scale. Thus if a mineral is scratched by quartz but not by orthoclase, its hardness is 6. Cleavage. Many minerals possess the property of splitting more or less readily in certain directions. This is termed the cleavage. Some minerals exhibit but one system of cleavage planes, others two or three. These cleavage systems intersect each other at definite angles. In orthoclase feldspar, for exam- ple, the cleavage planes cause the mineral to break off with square corners. Cleavage planes may be parallel to crystal faces. Lustre. Minerals often show a more or less characteristic lustre on either the crystal faces, cleavage planes, or fracture surfaces. These lustres may be designated as vitreous, pearly, resinous, dull, earthy, metallic, etc. Quartz shows a vitreous lustre, and gypsum a pearly one. Form. If minerals have room to grow, they usually form crys- tals of definite outline, bounded by plane faces, but in most ROCK MINERALS AND ROCKS 7 rocks formed by the crystallization of minerals these are so crowded that they have no space to grow freely and complete their form. The grains are therefore termed crystalline. Having described briefly the common physical properties, the more important minerals found in building stones may next be taken up. Quartz. This mineral, which is composed of silica, is a very abundant one in many building stones. It is insoluble in all acids, except hydrofluoric, has a hardness of seven, no cleavage, a vitreous lustre, and a specific gravity of 2.6. If pure it is transparent and colorless, but more often it is milky white, and small amounts of impurities may give it differ- ent colors. It is very resistant to the weather. Flint and chert are amorphous or non-crystalline forms of silica, often of dark color, and form concretionary masses in certain rocks, especially limestones (Plate XXXI, Fig. i). Quartz is a common and important constituent of some igneous and metamorphic rocks and sandstones. Feldspars. The feldspars are essentially silicates of alumina, with potash, soda or lime. Orthoclase and plagioclase are species of feldspar. Orthoclase. This is a silicate of alumina and potash, but some of the latter may be replaced by soda. Its hardness is 6 and the specific gravity 2.54-2.56. It shows two sets of cleavage planes which intersect at right angles. Its lustre, on the cleavage planes, is somewhat glassy, and the color is commonly pink, sometimes very deep, less often whitish. Weathering destroys the lustre and, if carried to completion, converts the mineral into a white clayey mass. It is a common constituent of granites and many gneisses, and may be present in sandstones. Orthoclase is less durable than quartz, with which it is fre- quently associated, but is not to be regarded as unsafe on this account. Plagioclase Feldspars. Under this head are grouped several feldspar species, which are silicates of alumina with soda or lime. They agree with orthoclase in hardness, but range from 8 BUILDING STONES AND CLAY-PRODUCTS 2.62 to 2.75 in specific gravity. The plagioclases are usually white in color, and on certain cleavage planes show fine parallel lines. This, with their color, usually serves to distinguish them from orthoclase. They are less durable than the latter, but not sufficiently short-lived to cause the rejection of a stone containing them. Plagioclase is a common constituent of some igneous rocks, such as diorite, diabase and gabbro, in which quartz is rare or absent. Micas. Building stones, especially granites and gneisses, often contain two kinds of mica as prominent constituents. These are the white mica, or muscovite, and the black mica, or biotite. They are minerals of complex, as well as somewhat variable, chemical composition, but the former is essentially a silicate of alumina and potash, while the latter is a silicate of iron, alumina, magnesia and potash. They occur in the rocks in the form of small shining scales, sometimes of six-sided character, with a very perfect cleavage, which causes them to split readily into thin elastic leaves. Muscovite is silvery white in color, has a strong lustre, and is transparent in thin leaves. Its hardness is 2. -2. 5. Sericite is a very fine grained, silvery or light green type of muscovite, formed by the alteration of feldspar. Biotite is black or dark green in color, when in thick plates or masses, but differs but little from muscovite in its lustre, al- though its hardness is slightly greater, i.e., 2.5-3. Phlogopite, a nearly colorless mica resembling muscovite, is not uncommon in some crystalline limestones and serpentines. Of the several kinds of mica, the muscovite is little affected by the weather, but the biotite, on account of its high iron con- tent, is more liable to decompose on exposure to the weather. The kind, quantity and distribution of mica in a building stone exerts an important influence on its durability and work- ability. If present in abundance, and the scales are arranged in parallel layers, the rock may split readily along these planes. Such stones, especially sandstones, should be set on bed. ROCK MINERALS AND ROCKS 9 Mica, if abundant, is also an undesirable ingredient of marble used for exterior work, as it weathers out easily and leaves a pitted surface. It is difficult to polish and therefore affects the continuity of the polished surface of a rock containing it. Some building stones, such as granite, are rarely free from it, but in these it is not regarded as an injurious constituent unless present in large quantity. The micas may, on account of their color, exert a strong effect in this direction. Amphibole. This mineral, which is a complex silicate, has a number of varieties, of which hornblende is the most important in building stones. Tremolite is another. Hornblende is a silicate of iron, lime, magnesia and alumina. It is dark green, brown or black in color, and occurs in compact, sometimes bladed, crystals of fair lustre. It resembles biotite but does not split into thin leaves as the latter does. Its hard- ness is 5-6. Unlike biotite mica, hornblende takes a polish and shows a better resistance to the weather than that mineral. Hornblende is an important constituent of many igneous rocks and of some metamorphic gneisses and schists. Tremolite (Plate XXXI, Fig. 2) is a pale-green variety of amphibole found in some crystalline limestones. It occurs in blade-like or silky-looking masses and is a detrimental mineral, since it tends to decompose to a greenish-yellow clay. Pyroxene. This is a common mineral in some igneous rocks, especially the darker-colored or basic ones. Its composition and colors are similar to those of amphibole, from which it often cannot be distinguished with the naked eye when found in build- ing stones. The dark-colored variety, augite, is an essential constituent of some igneous rocks, such as diabase and basalt, but may occur in other more acid ones. Other varieties of pyroxene may be present in either igneous or metamorphic rocks but are not always visible to the naked eye. Augite takes a good polish and shows fair durability. Merrill states that the " pyroxene of the Quincy, Mass., granite proves to be an exceptionally brittle variety, and the continued 10 BUILDING STONES AND CLAY-PRODUCTS breaking away of little pieces during the process of dressing the stone makes the production of a perfectly smooth surface a matter of great difficulty. " Calcite. This mineral consists of carbonate of lime (CaCO 3 ). It is white, when pure, and has a hardness of 3 ; hence it is soft enough to be scratched with a knife. It effervesces readily when a drop of dilute acid is put on it. Calcite is an important, and sometimes the only, constituent of many limestones, marbles and onyxes. Calcareous shales contain a variable quantity of it. It may also, occur as a secondary constituent of many igneous rocks, having been formed by the decomposition of other minerals, but in such cases it is usually present in but small amounts. Sandstones may have some calcite as a cementing material. When exposed to the weather, calcite is dissolved by waters, especially those containing a little acid. The action is usually slow, but its effect is sometimes seen in limestone quarries where the rock has been dissolved out to a variable depth along the joint planes. Aragonite, which has the same chemical composition as cal- cite but differs from it in crystalline form and specific gravity, occurs in some onyx marbles. Dolomite. This mineral, which is a double carbonate of lime and magnesia, (CaMg)COs, is much like calcite, but differs from it in being slightly harder and in effervescing only with hot dilute acid. It is a common constituent of many limestones and marbles. Dolomite is less soluble in surface or rain waters than calcite but disintegrates more readily than the latter does. Gypsum. This is a hydrous sulphate of lime (CaSO 4 + 2 H 2 O) and is not present in many building stones; indeed, it occurs only in stratified rocks. The mineral is soft enough to be scratched with the thumb nail, and its softness, together with the fact that it is not acted on by acids, serve to distinguish it from calcite. Alabaster is a fine-grained, white variety, showing a trans- lucency in thin plates. ROCK MINERALS AND ROCKS II Gypsum, though occurring in beds, is of little value for struc- tural work. Serpentine. Serpentine is a green or yellowish material, of soapy feel, without cleavage and soft enough to be easily cut with a knife. Chemically it is a hydrous silicate of magnesia (M g3 Si 2 7 + 2 H 2 0). It is a common and important constituent of the serpentine or verd antique marbles used for decorative work, and in these occurs mixed with calcite or dolomite. Its low resistance to the weather is mentioned later. Talc or steatite is a hydrous magnesium silicate [H 2 Mg 3 (SiOs)^. It is very soft, softer even than gypsum, and occurs commonly in the form of small greenish scales. It resembles mica, but the soapy feel, softness, and absence of elasticity in the scales serve to distinguish it from that mineral. It is commonly an alteration product of minerals such as horn- blende, augite, mica, etc. When it occurs in massive, somewhat impure form it is called soapstone, a material extensively used for sinks, washtubs, etc. Olivine. This mineral, known also as chrysolite and peridot, is a silicate of iron and magnesia [(MgFe^SiOJ. It has a hardness of 6-7, glassy lustre, and is often of bottle- green color, so that the rounded grains, if fresh, are easily recog- nizable in certain rocks, of which they sometimes form a charac- teristic ingredient. Olivine changes easily to serpentine. Garnet. A silicate of alumina, lime, iron or magnesia, whose hardness is 6-7, color often red, and occurring in rounded grains. It is not uncommon in some rocks, such as mica schist, gneiss, granite or crystalline limestone. The color and form cause garnets to be readily recognized. Garnets are undesirable constituents of building stones, as, owing to their brittleness and hardness, they break away from the stone in the process of dressing and interfere with the pro- duction of a smooth surface. Chlorite is a micaceous mineral or group of minerals which occur as secondary products in some igneous and metamorphic rocks and may impart a green color to them. 12 BUILDING STONES AND CLAY-PRODUCTS Pyrite or Iron Pyrite, an iron disulphide (FeS 2 ), is common in all kinds of rocks. Its yellow color and metallic lustre make it easily recognizable. When in grains large enough to be seen, it is found to form small cubes or irregular masses. It is an undesirable constituent of building stones, especially ornamental ones, since it weathers somewhat easily to limonite, producing a rusty stain or causing disintegration of the rock. Another form of iron sulphide, marcasite, decomposes even more readily. Magnetite, or magnetic iron ore (Fe 3 O4), occurs as minute grains in many dark-colored igneous rocks (diabase, basalt, etc.), but is usually identifiable only on microscopic examination. On exposure to the atmosphere it may change to the sesqui- oxide, causing a rusty stain on the rock. Limonite, a hydrous oxide of iron (2 Fe 2 3 , 3 H 2 0), is a com- mon cement of many rocks, and is also formed by the decom- position of pyrite, and of iron-bearing silicates such as biotite, hornblende or garnet. It is of a yellowish-brown or brown color and non-crystalline character. ROCKS. 1 A rock may be defined as a natural aggregation of minerals forming a portion of the earth's crust. According to their mode of origin, rocks can be divided into three great groups, the igneous, stratified and metamorphic. The origin and essential characters of these may be briefly referred to. IGNEOUS ROCKS. These have been formed by the cooling of a molten mass, or magma, which has come up from some variable and unknown depth in the earth's interior. As it cooled, the different minerals crystallized out to form a more or less tightly interlocking mass. The rock in some cases has solidified before reaching the surface, while in others it has flowed out on the surface as a lava stream. 1 For more details than can be given here see Scott, "Introduction to Geol- ogy" (Macmillan Co.); Kemp, "Handbook of Rocks" (Van Nostrand); Pirsson, 'Rocks and Rock Minerals" (Wiley and Sons). PLATE I. A small fine-grained dike of dark diabase cutting a lighter-colored syenite. These dikes may be very narrow, or many feet in width. PLATE II. A volcanic rock, trachyte, showing porphyritic texture. ROCK MINERALS AND ROCKS 17 Those which cooled below ground are known as plutonic rocks and show varying forms, while those which have cooled on the surface are termed volcanic rocks. Some masses of igneous rock are long and narrow (dikes), while others are irregular, or rudely dome-shaped in character (bathyliths and bosses). With few exceptions, they agree in being of a massive struc- ture, more or less crystalline in texture, and free from strati- fication planes. They differ in their texture, however, some being fine grained, others coarse grained. Some are even textured (Plate III, Fig. i), while others show a groundmass of small crystalline grains, embedded in which are larger ones, often of distinct crystal outline; this latter type of texture is termed porphyritic (Plate II). In some cases lavas approaching the surface in the vent of a volcano are blown out with such force as to be disrupted into a mass of large and small fragments, which settle down on the surface. The coarser material is often called volcanic breccia, while the finer-grained deposit is termed tuff or ash. These ash deposits become subsequently cemented somewhat by the action of rain water. In some countries, as Mexico, volcanic breccias and tuffs are extensively used for building purposes. Igneous rocks are differentiated or classified on the basis of their mineralogical composition and texture. The volcanic rocks may be glassy, cellular or porphyritic. The plutonic ones are usually massive and holocrystalline, por- phyritic textures being rare, except in the dike rocks. A rock might, therefore, preserve a uniform mineral composi- tion, but vary in its texture, depending upon the conditions under which it cooled. On the other hand, several plutonic rocks might agree in their texture, but differ in their mineralogical make-up. These differences, either mineralogical or textural, lead to the development of different species. The following table, taken from Pirsson, expresses simply the mineralogical and textural relationships of the more common types : i8 BUILDING STONES AND CLAY-PRODUCTS A. Grained, Constituent Grains Recognizable, Mostly Intrusive. Non-porphyritic. a. Feldspathic rocks, usually light in color. b. Ferromagnesian rocks, generally dark in color to black. With quartz. Without quartz. With subordinate feldspar. Without feldspar. Granite. Syenite, a. Syenite. Anorthosite. Diorite. Gabbro. Dolerite. Diabase. Peridotite. Pyroxenite. Porphyritic. Granite porphyry. Syenite porphyry. Diorite porphyry. B. Dense, Constituents Nearly or Wholly Unrecognizable. Intrusive and Extrusive. Non-porphyritic. a. Light colored, usually felds- pathic. b. Dark colored to black, usually ferromagnesian. Felsite. Basalt. Porphyritic. Felsite porphyry. Basalt porphyry. C. Rocks Composed Wholly or in Part of Glass, Extrusive. Non-porphyritic. Obsidian, pitchstone, pumice. Porphyritic. Vitrophyre. D. Fragmental Igneous Material. Extrusive. Tuffs, Breccias (Volcanic ashes, etc.) The above classification includes nearly all the more impor- tant rocks which are used for building purposes. There are many others but they are rarely used for structural or monu- mental work. Those mentioned in the above table may now be briefly denned. Granites (Plates III, IV). These consist essentially of quartz, orthoclase feldspar (sometimes microcline). Some species of mica, amphibole or pyroxene is usually present, and a number of others may occur as accessories, but they are usually of micro- scopic size. The texture is holocrystalline but varies from coarse to fine. Granites are sometimes classified according to some prominent accessory mineral, as muscovite, etc. Pegmatite (Plate V) is a granite, usually of very coarse grain, and occurring commonly in the form of dikes. It is of no value PLATE III, Fig. i. Moderately fine-grained granite, Hallowell, Me. PLATE III, Fig. 2. Very coarse-grained granite, St. Cloud, Minn. PLATE IV. Coarse-grained, somewhat porphyritic granite from Crotch Island, Me. 21 ROCK MINERALS AND ROCKS 23 as a building stone, but the occurrence of dikes of it in some quarries causes a serious waste. Syenite. This is an even granular rock, composed chiefly of orthoclase feldspar and differing from granite only in the absence of quartz. Mica, hornblende or pyroxene are usually present. Syenites are sometimes porphyritic and grade into syenite porphyry. They may be white, pink or gray in color. They are not very abundant, and are of little importance as building stones. Diorite. This is a granular intrusive rock composed of horn- blende and feldspar, but often containing considerable biotite mica. The feldspar is a plagioclase. Diorites are of a dark gray or greenish color, sometimes nearly black, while the grain varies from coarse to fine. Intermediate forms between granite and diorite are known as granite-diorite. Monzoniie is intermediate between syenite and diorite. Gabbro. This is also a granular intrusive rock, which consists chiefly of pyroxene and feldspar. The latter may predominate to such an extent as to give the stone a very dark color. The color is dark gray or greenish to black. Magnetite in small black grains is often present, and so, too, may be olivine. It is a common rock in the United States, being known in New England, the Adirondacks, in Maryland, Minnesota, the Rocky Mountains and California. Though of value as a building stone, its dark color causes gabbro to be avoided. Peridotite. A granular intrusive igneous rock composed of olivine and pyroxene without feldspar. It is mostly very dark in color. Pyroxenite. This is also a granular plutonic rock, whose chief mineral is pyroxene, but which lacks olivine. Granite Porphyry. A rock of porphyritic texture and same mineral composition as granite. Syenite Porphyry. A porphyritic rock with phenocrysts of feldspar in a groundmass consisting chiefly of feldspar. The dark minerals biotite, hornblende or pyroxene may be present. 24 BUILDING STONES AND CLAY-PRODUCTS Diorite Porphyry. Consists of phenocrysts of hornblende and feldspar in a groundmass of the same minerals , Felsite. This is a general term which includes fine-grained igneous rocks of stony texture and usually light color. They correspond to granites and syenites in mineralogical composition. In many cases the mineral grains are too small to be seen with the naked eye. If of porphyritic character, and the phenocrysts are quartz, the rock may be called rhyolite, while if the phenocrysts are feldspar the name trachyte porphyry is used. Felsites occur as dikes or more often as lava flows or sheets. They are not uncommon in many parts of the United States. Basalts. These correspond to the felsites in texture but are dark colored. Mineralogically they agree with gabbros or diorites. They are gray black to black in color, but their appear- ance is less lustrous than that of many felsites. Basalt porphyry bears the same relation to basalt that fel- site porphyry does to felsite. STRATIFIED ROCKS. This group includes a series of rocks of stratified character (Plate VI); that is to say, they are made up of layers. They consist of material which has been derived from pre- existing ones. To state their origin briefly it may be said that when rocks are attacked by the weathering agents they are broken down by physical and chemical processes. Some of the products of decay, consisting of rock and mineral fragments, are washed down the slopes into the streams and carried by them to the lakes or sea, on the floor of which the material settles down as sediment. Additional quantities may be supplied by waves beating against the rocks exposed along the shore. Other portions of the rock masses referred to above are carried off in solution and reprecipitated, perhaps as chem- ical sediments, on the ocean floor or sometimes on the land, as in caves, ponds or around the mouths of springs. 1 1 There are other methods of accumulation but these are the most important. PLATE V. Pegmatite, showing coarse-grained texture. PLATE VI, FIG. i. View in a limestone quarry, showing the horizontal stratification planes and vertical joint planes. (H. Ries, photo.) PLATE VI, FIG. 2. General view of a limestone quarry, showing stratified character of the rock. ROCK MINERALS AND ROCKS 29 The accumulation of shell fragments on the ocean bottom may also cause deposits of considerable size and extent. These ocean sediments may collect in considerable thickness and become consolidated (hardened) , in part by pressure of many feet of overlying beds, and in part by the deposition of mineral matter around the grains, which serves as a cement to bind them together. Later, by the uplift of the ocean bottom, such rock masses become elevated to form land. Some stratified rocks, however, as sand, gravel and clay, may still remain soft. The more important types may be defined. Sandstone. This is a rock of varying hardness, whose grains are chiefly quartz. These grains are of varying size and are bound together usually by silica or iron oxide, although lime carbonate and even clay may also perform this function. A micaceous sandstone is one containing mica scales. Argil- laceous sandstone is a fine-grained phase containing considerable clay. Arkose is a variety containing much feldspar. Conglomerate. This might be defined as a cemented gravel, the pebbles of which are more or less rounded, and may be of different kinds of rock. Conglomerates vary in their coarseness, and all gradations from a coarse quartz conglomerate to a sand- stone may be found. Shale. This is a thinly layered clay rock formed by the con- solidation of clay. It is of no value as a building stone. Limestone. A rock consisting, when pure, of lime carbonate or calcite and showing varying degrees of purity, hardness and texture. Sand and clay are common impurities and by an in- crease in these the rock may pass into sandstone and shale. Some varieties contain large quantities of shells and other fossils, which may stand out prominently on the weathered surface. Limestones vary in their color but white, gray or black are common ones. They are usually fine-grained. A drop of acid causes violent effervescence. Of the varieties of limestones, the following are worth mention- ing in this connection: 30 BUILDING STONES AND CLAY-PRODUCTS Chalk, a very soft limestone of earthy texture and usually white in color. Calcareous tufa, a porous mass of lime carbonate, deposited around the mouth of springs, as in swamps. It often coats the plants growing in that locality. Travertine is formed in a similar way but is more massive. Onyx, a dense, crystalline form of lime carbonate, deposited usually on the floor of caves by percolating water carrying lime. Coquina. A loosely cemented shell aggregate like that found near St. Augustine, Fla. Dolomite. A rock composed of the carbonate of lime and magnesia. It resembles limestone in its hardness and color but often presents a more sandy appearance on the weathered sur- face. Effervescence is produced only with warm acid. There is no sharp line of division between limestone and dolo- mite, the two grading into each other. METAMORPHIC ROCKS. Both igneous and stratified rocks sometimes become deeply buried in the earth's crust, in which position they may be sub- jected to great pressure or heat, or sometimes both. Without going into the causes of this, it may be simply stated that as a result of these two forces acting on the kinds of rocks above mentioned, they are often profoundly changed in their structure, texture, density and even mineral composition. Metamorphic rocks usually show a crystalline or grained structure; they are dense and sometimes banded. Certain ones, like slate, split very regularly or with a perfect cleavage. Some rocks may be locally metamorphosed by intrusions of igneous rock. The following are important types of metamorphic rocks: Quartzite. A hard siliceous rock derived from sandstone and differing from the latter in being harder and denser. Slate. A clay rock produced by the metamorphism of shale. In the process of change, the original stratification planes often become closed up, their position being indicated by the so-called ribbons in the slate. A new plane of splitting, known as the ROCK MINERALS AND ROCKS 31 cleavage, is developed, and it is the regularity and perfection of this which makes the slate of value for roofing purposes. By further metamorphism a slate may pass into a schist. (See below.) The usual color of slate is dark gray or bluish black, but red, green and purple ones are also known. Phyllite is a slate in a more advanced stage of metamorphism, and one in which the mica scales are not only more abundant but also visible to the naked eye. Marble is a metamorphosed limestone. It is of crystalline or grained texture and may be either dolomitic or not. Clayey impurities that were present in the original rock have often been transformed into silicate minerals such as mica, these new minerals being frequently arranged in lines or belts, thus giving the rock a banded structure. Such marbles are far less resistant to the weather. Carbonaceous matter may cause gray colora- tion, sometimes of a streaky or banded character. Marbles are affected by acid in the same manner as their unmetamorphosed equivalents. Ophicalcite is a crystalline limestone with grains or patches of serpentine. Gneiss (Plate VII). This is a banded or laminated metamor- phic rock, which corresponds in its mineralogical composition to granite or some other plutonic rock. Thus we might have a granitic gneiss, a syenitic gneiss, etc. Schist. This is more thinly foliated than gneiss, due usually to an excess of bladed or scaly mineral grains such as mica. The different varieties are named after some prominent component mineral such as mica schist, hornblende schist, quartz schist, etc. Owing to their thin and irregular foliations, schists are of little value as building stones. Schists may grade into gneisses on the one hand and into slates on the other. STRUCTURAL FEATURES AFFECTING QUARRYING. Two important structural features, which affect quarrying operations and also the market value of the stone, are bedding and joints. 32 BUILDING STONES AND CLAY-PRODUCTS Bedding (Plate VI). This refers to the separation of the rock into layers and is found in all stratified rocks. In some areas the rocks are in an undisturbed position and the layers are hori- zontal, while in other portions of the earth's crust the rocks have been disturbed by folding since their formation and the beds show varying degrees of tilt or dip. The position of the beds is of importance. If they lie nearly horizontal, quarrying is begun in the upper layer, and only one bed can be quarried at a time. Moreover, if the good beds are covered by worthless ones, these latter must be first removed. When a quarry is opened in a hillside, or where the beds are steeply upturned, the material in the different layers can be quarried at the same time, and thus one quarry is capable of producing several kinds of stone. The marbles of Vermont are a good example of this, for there can be produced, at the same time from the various beds, marbles of pure white, cloudy, light water blue and dark bluish and greenish tints. The bedding planes vary in their spacing in different quarries. In some they are widely separated, and consequently the rock is very massive and more expensive to quarry, although blocks of considerable thickness can be obtained. In others the layers are very thin, and few stones of value are obtainable, but these thinly bedded rocks, if of sandy nature, are sometimes of value for flagging. Stratified rocks split somewhat readily along their bedding planes. Joints (Plates VI and XX). These are present in all kinds of rocks and represent fissures of varying length produced by several causes, such as shrinkage, twisting, crushing, etc. Joints may traverse the rocks in different directions, and those which are parallel are regarded as belonging to the same series. There may be one or more series of vertical joints and a set of horizontal ones, these combining to break the rock into blocks of rectangular or cubical character. Joints are an advantage in that they facilitate the extraction of the stone. They are a disadvantage if they serve as a path- PLATE VII. Biotite gneiss, showing characteristic banded structure of this rock. 33 ROCK MINERALS AND ROCKS 35 way for surface waters and weathering agents to enter the rock, and, moreover, they limit the size of the blocks that can be extracted from the quarry. In some cases an otherwise good stone may be so cut up by joints as to be rendered worthless for any purpose except road material. CHAPTER II. PROPERTIES OF BUILDING STONE. THE properties which have an important bearing on the value or durability of a stone, or on both, are: Texture, hardness, color, density, absorption, strength, resistance to frost, fire, abrasion or acid vapors, and chemical composition. Many of these exert a direct or an indirect influence on the durability or life of a building stone, which will be referred to in more detail later. The properties enumerated above may next be taken up in some detail, as they are nearly all of importance. Texture. By texture is meant the grain of the stone. This may vary from coarse to fine or from regular to irregular. Most limestones are fine-grained. Sandstones, though commonly fine-grained, may show a coarse texture if representing transi- tional phases to a conglomerate. Marbles vary from the finest textured forms, like those of Carrara, Italy, and Alabama, to others so coarse as to be unde- sirable for structural work. Similar variations exist in igneous rocks. Many of the latter may also show a porphyritic texture. Fine-grained rocks, whose grains are closely fitting, are denser and may also be more durable. This is especially true in granites, the finer- textured ones being of longer life than the coarse- grained and the porphyritic ones. If the mineral particles are not only large but of unequal hardness, the softer ones disintegrate more readily, thus leaving small pits on the surface. Cleavage cracks may also open up more easily in the large than in the small mineral grains. Hardness. The hardness of a rock and the hardness of its component minerals should not be confused. The former depends on several factors, such as hardness of component minerals and relative abundance and state of aggregation. A 36 PROPERTIES OF BUILDING STONE 37 rock may therefore consist entirely of hard quartz grains and yet be bound together by so little cement that it will crumble under very little pressure. Another one similarly composed of quartz grains may be so well cemented by silica as to show a high crushing strength. Hawes 1 has shown that the hardness of certain granites, for example, is not due entirely to quartz, which is hard and brittle and crushes under the tools, but that it is due to the feldspar, which is of variable hardness and has different cleavages. Although hardness is an important quality there is no standard method of testing it, but the following ones are sometimes used. Rosiwal, adopting Toula's principle, 2 uses a piece of smooth but unpolished granite of about 2 grams' weight and rubs it with emery (of 0.2 mm. diameter grain) upon a glass or metal plate for from 6 to 8 minutes until the emery loses its effectiveness. The granite is then weighed and its loss of volume calculated. Such a test is rather inaccurate. A test suggested by J. F. Williams 3 consisted in noting the rate of penetration of a drill of a given diameter, or by measuring the distance to which such a drill will penetrate without being sharpened; or it might be possible to determine the amount of rough-pointed surface that could be reduced to bush-hammered surface in an hour. To make this last test of value a pneumatic drill or surfacer should be used. Color. Building stones may show a variety of colors, including white, brown, red, yellow, gray, buff, black, etc. These colors, in many cases, are really of a composite character, being produced by a blending of the colors of the individual minerals. Uni- formity of color may be produced by uniformity of distribution of the mineral grains or by the rock being composed entirely of one mineral. Among the igneous rocks, of which granite is the most commonly used for building purposes, a variety of colors is observable. Reds and grays, both common colors in granite, 1 Tenth Census, X, pp. 16-18, 1888. 2 Verhandl. K. k. geol. Reichsanstalt, 1896, p. 488, and quoted by Dale. 3 Ann. Rep. Ark. Geol. Surv., I, 1890, p. 41. 38 BUILDING STONES AND CLAY-PRODUCTS are dependent on the proportion of red and white feldspar. A granite of white feldspar and quartz and muscovite mica is very light in color, especially if dressed with a smooth surface. Gray and dark gray granites often owe their color to an excess or appreciable quantity of dark minerals, such as pyroxene, horn- blende and biotite. Some igneous rocks with labrador feldspar have a distinctly iridescent color. The volcanic rocks may be either light or dark colored, depending on their mineral composition, some being even black. Some diorites, gabbros and diabases not un- commonly show a dull greenish-gray color. Among the sedimentary rocks the different shades of brown, red, buff and yellow are due mainly to the occurrence of iron oxide. Gray, blue and black are commonly produced by car- bonaceous matter. The white color of sandstones indicates the presence of clean quartz grains, while the same color in limestone is due to the predominance of calcite or dolomite. In the metamorphic rocks the colors of marbles and quartzites are due to the same causes as in limestones and sandstones. Gneisses owe their color to that of the individual grains. Variation in Color. Sedimentary rocks occasionally show a variation in color, not only in the same quarry but even within short distances in the same bed. This is commonly due to irreg- ularity of distribution of the coloring material, which may be disposed in regular bands or irregular spots. In granites variations in color may be due to an increase or a decrease in the proportion of certain minerals in different parts of the quarry. Some granites show dark and unsightly spots, caused by the segregation of the darker minerals. Change of Color. This may occur after the stone has been quarried. In stones colored black or gray by carbonaceous matter a slight fading is some tines noticeable. Some bright pink granites have also been known to fade on continued expos- ure to the sunlight. Certain sandstones, though white or light gray when freshly quarried, may, on exposure, change to buff or brown, owing to changes within the rock. These changes do not necessarily represent a weakening of the stone. PROPERTIES OF BUILDING STONE 39 The Berea sandstone of Ohio changes to a buff color after a few years' exposure, due to the alteration of finely divided pyrite to limonite. In such cases no harm results, but if the iron sulphide (pyrite) is in large grains or lumps the limonite result- ing from it may be carried in streaks over the surface of the stone, greatly marring its appearance. 1 A whitish discoloration seen on the surface of some stones is an efflorescence derived from soluble salts, contained within the pores of the rock. It is brought to the surface by evaporation of water contained in the pores of the stone. In some instances it is traceable to the mortar. Dust from the atmosphere will speedily discolor many light stones, and hence the use of white marble for exterior work is to be avoided in many cities where soft coal is extensively used. Architects, however, often show a cheerful disregard for such precautions. Such dirt will naturally adhere more strongly to a rough than to a smooth surface. Some green slates are liable to change color on exposure to the atmosphere, but this does not necessarily indicate loss of strength. The permanence of color of a stone can oftentimes be gauged by a comparison of the fresh face and weathered outcrop at the quarry. An important property is the contrast which a stone shows between hammered and polished surfaces. It has to be con- sidered if the stone is to be used for monumental or inscriptional work, and is most pronounced in those stones containing a greater abundance of transparent feldspar and darker minerals. Remarkable as it may seem, fashion is a potent factor in the selection of building stones. Some years ago brownstone was used in unlimited quantities, and the monotonous rows of brownstone houses to be seen in many eastern cities attest the craze for this material. Incidentally, it was a costly one, for 1 Streaking of a stone is sometimes caused by the mortar colors becoming washed out of the mortar joints. A custom, thoughtlessly pursued by some archi- tects, is to fasten ironwork into the surface of a light stone, with the result that the rust from the iron invariably produces unsightly streaks 40 BUILDING STONES AND CLAY-PRODUCTS dozens of these buildings show the stone to be disintegrating, because it was placed on edge instead of on bed. Now the Berea sandstone and Bedford limestones are most used. One asks, What next? Polish. The ability of a stone to take a polish depends on its density and the character of the mineral constituents. An aggregation of the same minerals, or even different minerals of the same hardness, permits of the development of a better polish than a mixture of minerals of varying hardness. Quartz, feld- spar and calcite take a good polish, while hornblende and augite are less favorable. Micas are difficult to polish. Specific Gravity and Porosity. The specific gravity of a stone is the weight of the stone compared with that of an equal volume of water. In order to determine it the stone should be first weighed dry; it should then be saturated as nearly as possible by boiling in distilled water, and weighed suspended in water. The specific gravity then is r D G = ^s' in which .,. G = specific gravity D = dry weight, 5 = suspended weight. The average specific gravity of a number of stones is given by Hermann as follows: Granite 2.65 Basalt 2.9 uartz porphyry 2.6 Lava 2.15 yenite 2.8 Gneiss 2.65 Diabase 2.8 Clay slate 2.7 Diorite 2.8 Limestone 2.6 Gabbro 2.95 Dolomite 2.8 Serpentine 2.6 Gypsum 2.3 Trachyte and andesite. . . 2.7 Sandstone 2.1 The weight of the dry stone per cubic foot is obtained by multiplying its specific gravity by the weight of a cubic foot of water (62.8 pounds), but Buckley suggests there should be de- ducted from this the weight of a quantity of stone of the same specific gravity equal in volume to the percentage of the pore space of the stone. PLATE VIII, Fig. i. Gray marble, Gouverneur, N. Y., showing contrast between tooled and polished surface. PLATE VIII, Fig. 2. Gabbro from Keeseville, N. Y., showing contrast between tooled and polished surface. 41 PROPERTIES OF BUILDING STONE 43 The porosity is obtained by the formula P = 100 \W \ -S in which P = per cent porosity, W = saturated weight, D = dry weight, 5 = suspended weight of saturated stone. Foerster 1 gives the following porosity determinations as made by Hauenschild and Lang. POROSITY PERCENTAGE OF DIFFERENT STONES. Granite 0.04-0.61 Syenite i .38 Diorite 0.25 Porphyry o. 29-2 . 75 Basalt 1.28 Diabase breccia o. 18 Trachyte tuff 25.07 Serpentine 0.56 Sandstones: von Sailing 6.9 Nebraer 25.5 Keuper 16.94 Carrara marble 0.22 Tufa 32.2 Roofing slates 0.045-0.115 Buckley's work on Wisconsin Building Stones 2 gives the fol- lowing range of porosity: Granites .... Limestones . Sandstones . 0.019- 0.62 o-55 -13-36 4.81 -28.28 Determinations made by the same writer on Missouri stones 3 gave: Granites Limestone Sandstone . . 0.255- 1-452 0.32 -13.38 7.01 -23.77 It is contended by some that it is of more importance to deter- mine the porosity than the absorption since the latter does not show the amount of water the stone is capable of holding and because there is no fixed ratio between pore space and absorp- tion; moreover that the porosity together with the size of the 1 Baumaterialienkunde, I, p. 13. 2 Wis. Geol. & Nat. Hist. Surv. Bull. IV, p. 400, 1898. 3 Mo. Bur. Geol. & Mines, II, 2nd Series, p. 317, 1904, 44 BUILDING STONES AND CLAY-PRODUCTS pores gives us a better index of the frost-resisting qualities. Stones of high porosity, but small pores are presumably less resistant to frost than those of high porosity and large pores. It must be admitted, however, that in general a stone of high porosity shows high absorption, and that the determination of the latter gives us a rough index of the porosity. Absorption. By this term is meant the amount of water which a stone will absorb when immersed in this liquid, and it should not be confused with porosity or the volume of pore space. While stones with low porosity can absorb little water, and others with high porosity may absorb considerable water, never- theless the absorption does not necessarily stand in any direct relation to the volume of pore space. A high absorption is considered undesirable, as the freezing of the water in the pores of the stone may cause it to disintegrate, but this injury is often more pronounced in fine-grained than in coarse-grained materials, for the reason that in the former the -water can drain off less readily. Dense rocks, like granites, gneisses, slates, marbles, many limestones and quartzites, usually show a very low absorption, often under i per cent. Other rocks including many sand- stones, some limestones (especially soft ones) and volcanic rocks like tuffs, may absorb from perhaps 2 up to 15 per cent of water. Quarry Water. Many rocks, especially those of the sedimen- tary class, contain water in their pores when first quarried. This is known as quarry water, and may be present in some stratified rocks, such as sandstones, in sufficient quantities to interfere with the quarrying of them during freezing weather. The quarry water usually contains mineral matter in solution, and when the liquid evaporates, as the stone dries out, the former is left deposited between the grains, often in sufficient quantities to perceptibly harden the rock. Crushing Strength. This is a property to which undue im- portance has probably been attached; indeed in some cases it may be the only test that is made on a stone. It can be safely assumed, as one writer has said, that a stone which " is so weak PLATE IX, Fig. i. Photomicrograph of a section of granite. (Photo by A. B. Cushman, from Ries's "Economic Geology.") PLATE IX, Fig. 2. Photomicrograph of a section of diabase. (Photo by A. B. Cushman, from Ries's "Economic Geology.") 45 PLATE X. Photomicrograph of a section of quartzitic sandstone. (From Ries's "Economic Geology.") 47 PROPERTIES OF BUILDING STONE 49 as to be likely to crush in the walls of a building, or even in a window stool, cap or pillar, bears such visible marks of its unfit- ness as to deceive no one with more than an extremely rudi- mentary knowledge on the subject." Few stones will, when tested, show a strength of under 6000 pounds per square inch, and many, especially igneous ones, stand as high, 20,000 to 30,000 pounds per square inch. To be sure, in some large buildings a single column or block may be called upon to carry a heavy load, but even then it prob- ably does not approach the limit of strength of the stone. Merrill has shown that the stone at the base of the Washing- ton monument supports a maximum pressure of 22.658 tons per square foot, or 314.6 pounds per square inch. Allowing a factor of safety of twenty would only require the stone at the base of the monument to sustain 6292 pounds per square inch. Even at the base of the tallest build- ings the pressure is probably not more than 160 pounds per square inch. The crushing strength of a stone is commonly obtained by breaking a cube (usually 2-inch) in a special testing machine. Great care should be taken to see that the cubes are prepared with the sides smooth and exactly parallel. In some cases, instead of preparing the surface of the cube carefully, it is only made approximately smooth and bedded between the plates of the machine with pasteboard or plaster of Paris. Unfortunately there is no standard size of cube used for test- ing purposes, and this may lead to variable results since the crushing strength per square inch does not appear to vary directly as the size of the cube. All cubes should be thoroughly dried before testing. The crushing strength of a stone is dependent on the state of aggregation of the mineral particles. In sedimentary rocks it depends on the character and amount of cementing material (Plate X) , while in igneous and metamorphic rocks it is depend- ent on the interlocking of the mineral grains (Plate IX). This interknitting of the minerals produces a higher crushing strength in the two last-named classes of rocks. 50 BUILDING STONES AND CLAY-PRODUCTS Many crushing tests have been published, but it is not always safe to compare them, because the conditions of testing have not been uniform. Wet stones show a lower crushing strength than dry ones, and exposure to repeated freezings may also lower the resistance to crushing. The following tests made by Buckley on Wisconsin stones show this to be true in some cases: CRUSHING STRENGTH OF WISCONSIN STONES BEFORE AND AFTER FREEZING. Kind of rock. Location. Crushing strength, fresh. Crushing strength, frozen. Granite Athelstane 19,988 10,619 do Berlin 24,800 36,000 do do 45,841 32,766 do Montello. ... .... 38,244 3^,O4<; Limestone Duck Creek 24,522 28,392 do Sturgeon Bay 35,970 20,777 do Wauwatosa 18,477 25,779 do Burlington 12,827 7,cc4 Sandstone Presque Isle C,4QC c, Q-2Q do Dunnville . . . 2,722 7,464 ..do.. Port Wing. . 5, 329 4,399 Additional figures are given by Watson for North Carolina sandstone. CRUSHING TESTS OF NORTH CAROLINA SANDSTONE. Percent absorption. Conditions. Crushing strength, Ibs. per sq. in. 42 fDry ^ Wet $ 10,322 ( 11,150 ( 6,962 1 [_ Frozen {Dry 7 ' 1 5>837 i 5,625 i 6,875 ( 12,250 371 Wet i 11,232 5,637 Frozen . . . ) 6,712 6, 2 8 7 1 6,500 PROPERTIES OF BUILDING STONE Tournaire and Michelot found that cubes of chalk 10 cm. in diameter showed a crushing strength, when wet, of 18.6 kilo- grams; when air dried, of 23.5 kilograms, and, when stove dried, of 86.2 kilograms. Stones usually weaken when subjected to continued or inter- mittent pressure, and may break considerably below their nor- mal ultimate crushing strength. However, great difficulty is experienced in obtaining satisfactory data on this point, for the reason that it is difficult to tell within a range of 1000 to 5000 pounds the crushing strength of samples to be tested (Buckley) . The following figures from tests by Buckley for Missouri and Wisconsin, and by Marston for Iowa, will give some idea of the variations which exist in the different groups of stones. State. Kind. Range, Ibs. per sq. in. Missouri Limestones 5,714-27,183 on bed. do do c,774 2CJ.C77 on edge do Sandstone 4,371 9,002 on bed do do 3,933 9,206 on edge do Granite 18,23619,410 average Wisconsin Igneous rocks 15,00947,674 do Limestone . 6,67542,787 on bed. do do 7,50840,453 on edge. do Sandstone 4,34013,669 on bed. ....do do 1,76312,566 on edge. Iowa Limestones 2,47016,435 do Sandstones 3,60013,000 Transverse Strength. The transverse strength represents the force required to break a bar i inch square resting on supports i inch apart, the load being applied in the middle. This is measured in terms of the modulus of rupture, which is computed from the formula: in which R R = modulus of rupture, w = weight required to break stone, / = distance between supports, b = width of stone, d = thickness of stone. BUILDING STONES AND CLAY-PRODUCTS The importance of this test has not been universally recog- nized, and it is therefore rarely carried out. Many a stone used for a window sill or cap has cracked under transverse strain (Fig. i), because its modulus of rupture in the section used is too low. Such transverse breaks are not uncommonly caused by the settling of the building. Fig. i. Sandstone broken by transverse strain-caused by settling of the building. It is of importance to note that the transverse strength does not appear to stand in any direct relation to the crushing strength. In a series of samples tested from Wisconsin and Missouri by E. R. Buckley, the following variation was noticed: MODULUS OF RUPTURE. Kind. Wisconsin. Missouri. Granite 2,324.33,909 . 7 Limestone 1,164.34,659 . 2 851 .303,311 .60 Sandstone 362 91,324 o 418 611,321 76 Of some interest also is the following set of tests taken from the Report on Tests of Metals, etc., for 1895, issued by the War Department. These represent the relative transverse strength of stones in the natural state and after exposure to hot and cold water baths. It will be noticed that in every case this treatment resulted in a lowering of the transverse strength. PROPERTIES OF BUILDING STONE 53 RELATIVE TRANSVERSE STRENGTH OF STONES IN NATURAL STATE AND AFTER EXPOSURE TO HOT AND COLD WATER BATHS. GRANITES. Description. Modulus of rupture per square inch. Natural state, total. After exposure to hot and cold water baths. Total. Loss. Per cent of natural state. From Braddock quarries, near Little Rock, Ark. Pounds. 1,704 2,069 1,423 1,378 1,415 2,335 Pounds. 1,244 2,027 1,230 1,053 1,083 2,OO2 Pounds. 460 42 193 325 332 333 From Millbridge, Me., " White Rock Moun- tain " From Rockville, Stearns County, Minn Drakes granite, from Sioux Falls, Minn From Branford, Conn From Troy, N. H Means. . 1. 721 I.AAO 281 8? 7 MARBLES. Rutland White, Vt Mountain Dark, Vt. ... 1,202 2.IOO 2QI 1 1,408 911 7OI Sutherland Falls, Vt From St. Joe, Ark FromDeKalb, St. Lawrence County, N. Y. 3,054 1,615 1,144 1,531 567 C77 1,523 1,048 611 From Kennesaw quarry, Tate, Ga 1,553 605 948 Means i,779 822 957 46.2 LIMESTONES. From Isle La Motte, Vt 2,403 786 I.7O7 From Mount Vernon, Ky i ,4.34. i 076 3*8 From Beaver, Carroll County, Ark. 2,860 2, 24.7 613 From Bowling Green, Ky. 1,^17 700 us Blue colored from Bedford, Indiana 1,867 0^8 ooo Means i,994 1,173 821 58.8 SANDSTONES. From Cromwell, Conn. 2,243 I ^OO 74.3 From Worcester quarry, East Long Meadow, Mass. . . .... 087 1,180 2O2 From Kibbe quarry, East Long Meadow, Mass 1,27"? 6tx 618 From Cabin Creek, Johnson County, Ark. . . Quarries near Fort Smith, Ark 2,442 I 761 890 I.lSe; 1,552 ^ 1^1 '%& z I -S ..S f|l g +J- ^^- ^ ^ ^ 2 ^C J3 243 XJ3J3 ^3 bo bCbibbo bObcbo S 5 3 3 j^'^ s - : I *** 1 . * * : ? ^gg 8 S 1 S w < ry ark bluis gray Dar gray (smoke color Dark gray with very sli tinge Yo Sou s I iJ : Light pinis gra dark purplish gray. Light pink mottled with d Dark yellow greenish gray ^ &: 8 | : fc o : Hi sn :b : ii i :6 : ^ ; Ai 3!! >>;. Bjffl S^J : : : s s : " 5 o o'S 5 5 : :0 2 rJ^o- : Il6 BUILDING STONES AND CLAY-PRODUCTS VERMONT. The commercial granites of Vermont are of three kinds: Biotite granite, quartz monzonite and hornblende-augite granite. To the first class belong those of Woodbury, Newark and most of Barre, to the second those of Bethel, Randolph, Rochester, Calais, Derby, Dummerston, Hardwick (Buffalo Hill), Kirby, Groton, Topsham, and some in Cabot. To the third, those of Mount Ascutney in Windsor. The Ryegate ones belong to both the first and second. A few may be mentioned briefly: Hardwick. The granite from the Buffalo Hill quarry, known as the " Dark Blue Hardwick" is a quartz monzonite of dark gray shade, a little darker than " Dark Barre" and a little lighter than 11 Dark Quincy." The -texture is medium. It is a bright granite with strong contrast between the white feldspar and black mica and takes a fair polish. It hammers light, offering a marked contrast to the polished surface. The latter shows some pyrite and magnetite. Bethel. This is known commercially as the " Bethel White Granite" and the "Hardwick White Granite." It is a quartz monzonite of very light color, medium texture, and relatively hard. It takes a high polish. Examples. Wisconsin State Capitol, Madison, Wis. ; Title Guarantee and Trust Co.'s Building, New York City; Old Colony Trust Company's Building, Boston, Mass.; Union Station, Plaza, Washington, D. C. Barre. To the southeast and northeast of the city of Barre there are about sixty quarries producing the lt Barre" granite. The stone is a biotite granite which owes its different shading partly to the varying content of biotite, and partly to different degrees of alteration of the feldspar. Dale names the following shades : (i) Very light gray (Wheaton quarry), equivalent to that of North Jay, Me.; (2) Light, in- clining to medium, slightly bluish gray (Jones light quarry), between that of North Jay and of Hallowell, Me.; (3) Light, medium bluish gray (Smith upper quarry), between that of Hallowell, Me., and Concord, N. H.; (4) Medium bluish gray (Duffee quarry), a trifle darker than " Concord granite;" (5) 10 O 10 ZO 30 40 MILES PLATE XXm. Map of Vermont showing granite centres and prospects. (After Dale, U. S. Geol. Surv., Bull. 404.) 117 IGNEOUS ROCKS (CHIEFLY GRANITES) AND GNEISSES 119 Dark, inclining to medium bluish gray (Bruce quarry) ; (6) Dark bluish gray (Marr & Gordon quarry) ; (7) Very dark bluish gray (Marr & Gordon quarry knots), equivalent to " Dark Quincy." The chief production is of 3, 4 and 5. Barre granite is used mainly for monumental purposes, a small quantity only being employed for constructional work. The light, medium and dark monumental granites do not afford strong mineral contrasts in the rough, but polishing improves this. The " light Barre" is never polished, but hammered, be- cause of the poor contrast between polished and hammered surface. The dark is often used in polished form. The Barre stone is perhaps one of the most extensively used in the United States and some large pieces have been taken out. Professor Perkins mentions one that was 95 feet long, 45 feet wide and 25 feet thick. Needless to say, this was not removed from the quarry in one piece. The largest finished pieces ever shipped from Barre were sent to Wheaton, 111., to be used as roof pieces for a mausoleum. Each was 35 feet long, 9 feet 4 inches wide, and i foot 4 inches thick. Another piece quarried was 51 by 4 by 4 feet, and was cut into a shaft which is now in Greenwood Cemetery, Brooklyn, N. Y. Examples. Calhoun Monument, Lexington, Ky.; Ohio and Iowa State Soldiers' Monuments, Chattanooga, Tenn.; State Soldiers' Monument, York, Pa.; Hearn Monument, with monolithic spire, 53 by 4 by 4 feet, Woodlawn, N. Y.; Gary Mausoleum with roof stones of the " light," 35 feet by 9 feet 6 inches, by i foot 6 inches each, Wheaton, 111.; First North Dakota Soldiers' Memorial, St. Paul, Minn.; Cluett Obelisk, with 44-foot shaft and pedestal, Troy, N. Y.; Holt- haus Monument, St. Louis, Mo.; Columns and capitols for Flood Mausoleum, San Francisco, Cal. Woodbury. This district supplies biotite granites of more or less bluish gray color, varying from dark to light shades, and very fine to medium texture. Examples. Pennsylvania State Capitol, Harrisburg, Pa.; Cook County Court House, Chicago, 111.; Syracuse University Library, Syracuse, N. Y.; Com- monwealth Trust Co., Pittsburg, Pa.; Post Office, Des Moines, la. Windsor. A green granite found on Mount Ascutney and classed mineralogically as a hornblende-augite granite. It is of dark olive-green color and medium texture. The stone takes a high polish and shows excellent contrast between the polished 120 BUILDING STONES AND CLAY-PRODUCTS and hammered surface; indeed it is one of the handsomest granites quarried in the United States. Examples. Sixteen polished columns (24 feet 9^ inches by 3 feet 7 inches) in Columbia University Library; Monument to General Gomez in Cuba; a die in the Bennington monument; thirty -four large columns in the Bank of Montreal; columns and die of W. C. T. U. fountain, Orange, Mass.; columns for interior of Temple of the Scottish Rite, Washington, D. C. MASSACHUSETTS. The igneous rocks and gneisses quarried in Massachusetts, and which could be grouped under the name of commercial granite, present considerable variety as to kind, texture and color. The important constructional ones are those of Milford, Fall River, New Bedford and Rockport. The Quincy granite in polished form is widely known because of its value for monuments. The most important granite quarrying centers are around Quincy, Rockport, Milford and Chester. Milford. A pink or pinkish gray or even greenish gray biotite granite, with spots of black mica, and of medium to coarse texture. The stone has a slightly gneissoid appearance, so that the spots are larger when the granite is cut parallel to the planes of foliation than when the faces intersect it at right angles. It takes a good polish and is extensively used for exterior and interior structural work. Examples. Eighty- four 3i-foot sectional columns for the new Pennsylvania Railroad Station, New York City; Twelfth Street Station, Illinois Central Rail- road, Chicago; John Hancock Insurance Company, Boston, Mass.; Rochester Safe Deposit and Trust Company, Rochester, N.Y.; Riggs National Bank, Washington, D. C.; Interior N. Y. Central R. R. Station, Albany, N. Y. Rockport. The quarries are on Cape Ann, Essex County, Massachusetts. The Rockport granite is of two sorts, viz., gray and green. The gray granite, the most abundantly known commercially, is a hornblende granite of medium gray color, spotted with black, and of a medium to coarse but even-grained texture. It is said to be a hard granite, due perhaps to its higher percentage of quartz, and takes a good polish. The green granite, which is also hornblendic, is of a somewhat dark, olive-gray color, spotted with black. The texture is me- dium to coarse, though even-grained. This stone, though dark gray when first quarried, becomes greenish after an exposure of 121 -"' fcJD fcJD X % X S3 123 IGNEOUS ROCKS (CHIEFLY GRANITES) AND GNEISSES 125 3 to 4 hours to the rain. It also fades slightly on continued ex- posure to the air. The stone takes a high polish, but shows less contrast between hammered and polished surface than the gray. Examples. Red: Real Estate Trust Company's Building, Philadelphia; American Baptist Publication Building, Philadelphia; Interior of Suffolk County Court House, Boston; Siegel Cooper Company Building, New York City. Gray Granite: Boston Post Office; Baltimore Post Office; Suffolk County Court House, Boston; National City Bank Building, New York City; Polished columns, Madison Square Presbyterian Church, New York City. Green Granite: Madison Avenue Church columns, New York City; Wain- scoting and stairways to the Towers of Philadelphia Public Buildings; Logan Monument, Chicago; two large polished bowls, Plaza Improvement, Union Station, Washington, D. C. Chester. A muscovite-biotite granite, of bluish-gray color and somewhat indefinite texture. It takes a fair polish and the hammered surface is light. Two varieties, the Chester dark and Chester light, are recognized. It is used chiefly for monuments, especially in Pennsylvania, New York and Michigan. Examples. Doctor Hoover Monument at Chambersburg and McCormack Monument at Pittsburg, Pa.; W. A. Harder Monument, Hudson, N. Y. Quincy. This is a hornblende-pyroxene granite. 1 The color is medium gray or bluish or greenish or purplish gray, to a very dark bluish gray, and dotted all over with black-appearing spots. The texture is medium to coarse, but even-grained. That which is used for monumental purposes goes under the names of "medium dark" and " extra dark." The " light" Quincy granite, which is of medium gray color, is considered second grade and sells for rock face and hammered work. Other and cheaper varieties suitable only for building purposes are the ' ' extra light " (pea green) , the pink and the greenish brown. Quincy granite is noted for its high and durable polish, and one quarry has supplied a polished ball 6 feet 6 inches in diameter. Examples. Gore Hall, Harvard University, Cambridge, Mass.; Custom House, New Orleans, La.; Payne Building, Cleveland, Ohio; Polished ball of "dark" granite, 6 feet 6 inches diameter, Rock Island, 111., cemetery; Bunker Hill Monument, Boston, Mass.; The Long Monument, Mansfield, Ohio. Classification of Massachusetts Granites. The following classification of Massachusetts granites is given by Dale, the term granite being used in the commerical sense. 1 Strictly speaking the minerals are riebeckite and aegirite. 126 BUILDING STONES AND CLAY-PRODUCTS 35 5 o o I o o w :g : : * ! - .2 : . 2 : : o : o : PQ : PQ : :ffi :K : I PQ PQ $*' 3 .-S o 1 s ; - Bl ." M "o v : .^ M cr-s o - o M llllli iji i : :s 'jo ; ' M : ^ .a" : : > M g-3& ^^c i^ 'g-ll, S 3 3fe sa PJ 53 II S^ gfe^ B-s-s a's-s sir Very Dark ^3 ^ ^ > ^- M .2 *3 .22 b >> 2 fl' "S 3 S - g M 1 1 1 * o > > > ' I s a a, p 2 2 2( i 1 i sit! i fli i > gj-C :s s. a -I II Lyn Pea ffi : , 6 t||sS ss g |3 :| I !b ; : sx 'y : : s I| Zl 1 a tf 3 S3 : >, V # fiTj :fc I o S^ :fi I to- rt : CCJ M ^83gg 11 1 fill! : aotuiuiuq. pan SntqanQ 128 BUILDING STONES AND CLAY-PRODUCTS RHODE ISLAND. Westerly. An important granite industry centers at this town and the neighboring one of Niantic. The " Westerly white statuary" is a quartz monzonite of more or less pinkish or buff medium gray color, and fine even-grained texture. The " Blue Westerly" is a quartz monzonite of more or less bluish, medium gray color, with fine black particles and of fine even-grained texture. " Red Westerly" is a biotite granite of reddish gray color, speckled with black, and of even-grained, medium, inclin- ing to coarse texture. The so-called " white" and the "blue" are strictly monumental granites, the former, especially, lending itself to the most delicate carvings. It takes a high polish and gives good contrast. The blue is about 50 per cent coarser than white and polishes not quite as well but gives just as good contrast. The red is used for structural work only. Examples. White Westerly : National Monument, Gettysburg, Pa. ; Antie- tam Monument, Md.; J. G. Fair Mausoleum, San Francisco. Examples of "Blue Westerly": Mutual Insurance Building, Hartford, and building of same Company in Philadelphia. Examples of "Red Westerly": Washington Life Insurance; American Tract Society and Travelers' Insurance Company buildings, New York City. Dale makes the following classification of the chief commercial granites of Rhode Island. Locality Trade name Color Texture Constructional Westerly, R. I. . . . Red Westerly Reddish gray Medium to coarse. Monumental . . . . j Westerly, R. I. . . Westerly, R. I. . . Blue Westerly.... White and pink Westerly. Blue medium gray. Pink or buff me- dium gray. Fine. Extremely fine. Inscriptional < Westerly, R. I. . . Westerly, R. I. . . Blue Westerly White and pink Westerly. Blue medium gray. Pinkish or buff medium gray. Fine. Extremely fine. Statuary Westerly, R.I... Westerly white statuary. Buff medium gray . Extremely fine. CONNECTICUT. The granites quarried in Connecticut are practically all granite- gneiss. Some of these are of the same mineral composition as a normal granite, while others are to be classed as quartz mon- zonite or mica-diorite gneisses. PLATE XXVI. Battle Monument, West Point, N. Y. Polished shaft of Branford granite, 41 feet 6 inches long and 6 feet in diameter. (Photo loaned by Norcross Bros.) 129 IGNEOUS ROCKS (CHIEFLY GRANITES) AND GNEISSES 131 Branford Township. This includes the well-known Stony Creek granite gneiss, and is denned as a biotite granite gneiss of medium reddish gray color, variable medium to coarse texture and gneissoid structure. The product is widely used for buildings, bridges and monuments. It takes an excellent polish. Examples. South Terminal Station, Boston; Bessemer Building, Pittsburg, Pa.; Newberry Library, Chicago; polished column (41 feet by 6 feet 2 inches at base) of Battle Monument, West Point; obelisk (45 feet long) at Locks Park, Sault Ste. Marie, American side; Erie County Savings Bank, Buffalo, N. Y. The Hoadley Neck quarries have supplied stone for pedestals of Statue of Liberty, New York Harbor, and of General Anderson Monument, Fort Sumter, S. C. Greenwich. The Greenwich blue-black granite is a mica dio- rite gneiss of dark bluish gray color, being darker even than the Quincy extra dark, and coarsely porphyritic gneissose texture. The rock is very tough and gives a brilliant surface; but the effect is different, depending on whether the grain face or hard- way face is exposed. The chief use of this stone is for buildings and massive struc- tures. Examples. Fort Schuyler on Throgs Neck, Long Island Sound; Episcopal Church, Port Washington, Long Island; Catholic Cathedral, Green Avenue, Brooklyn, N. Y. Waterford Township. A quartz-monzonite, known as " Con- necticut white " granite, is quarried south of Waterford Station. This rock is of medium buff gray shade, and fine, even-grained texture, and is a fine-grained monumental and inscriptional granite, without contrasts. It is finer than the Millstone granite and of lighter shade, but only about half as fine as the " Blue Westerly." It takes a high polish. Examples. Soldiers' Monument, Whitinsville, Mass.; Dudley Celtic Cross, Woodlawn Cemetery, N. Y.; Hoy Mausoleum, Mount Moriah Cemetery, Phila- delphia; City Deposit Bank, Pittsburg; Basement of Clark residence, Riverside Drive, New York City. Millstone. The stone from this locality is a quartz monzonite, between medium and dark gray smoke-colored, and even-grained granitic, fine texture. It is a brilliant stone for inscriptional and monumental purposes and takes a high polish. It hammers and cuts medium gray and thus affords an excellent contrast 132 BUILDING STONES AND CLAY-PRODUCTS between this and a polished surface. The texture is about one- third as fine as that of the coarser "Blue Westerly" granite. Examples. Saratoga Monument, interior entrance, and all but upper 10 feet of exterior; base, pedestal and cap of P. T. Barnum Monument, Bridgeport; George W. Childs mausoleum, Philadelphia. Groton. The several quarries at this locality yield a quartz- monzonite, of fine, granitic texture, and greenish color of slightly varying shade. It is a monumental granite, somewhat closely related to Blue Westerly, but about half as fine in texture. The polish between the cut and polished face is marked, a char- acteristic of all monzonites. Examples. William Ledyard Monument, Ledyard Cemetery, Groton; Ed- ward Newman Obelisk, Woodlawn Cemetery, New York; Rev. Byron A. Woods Sarcophagus, Forest Hills Cemetery, Philadelphia; Charles Tyler Statue, Druid Hill Ridge Cemetery, Baltimore; Beckwith and Rogers monuments, Cedar Grove Cemetery, New London. Among the other important quarries in Connecticut are those of the Glastonbury gneiss and Sterling granite gneiss, both used for curbing and trimming. A list of all the Connecticut quarries by Dale and Gregory and the kind of stone which they produce is given in summarized form below. IGNEOUS ROCKS (CHIEFLY GRANITES) AND GNEISSES 133 S S o >> ^5 >> g .03 cfl & : g ti ill -a h *d 2 ; -S s MM 3 i s i S : S S IllJl ^ : S^^ _w ; -d+3 " 2 te 1 1 ! *- T-** ^ W *r-J 4J l;a ml Ii ,1I I? a, a a j II : llf | 4 2S-]N* * : 91-11 a %% !l D ^2^-2 : bofe-g S : j WQ (U tifl D bO (D J bo"S o> 1 | r*. J | 5 lllllll & cr o- ? gO &-! I Ii f 1 I 1 3 ^pqffiffijQO:6^ScjS SO S & -S .a o- 1 I -H S i 1 I * I o 1 1 PQ ^- 01 I 1 cS | n o i >. a .^ 111 111 :| ij "d IS :S || o IS $Z C *-* S OCQ 3 ? ad St on. 511 111 Sw o R Hi " n J 3 : Q SST513 134 BUILDING STONES AND CLAY-PRODUCTS B-c S 3 3 3 33 II - JdJJ ar gr ay gra 1 ^ P3 2 i M yQ >> 3,2 G bO 6-s a >,>> few ^1 CJ r^ & >> a >^5 "3 o, i 2 2 Mg M sll 0) M 0) 11 III II I ni'3 feS ^ II 23 Mg, 's's 11 1 1?; i & o- 5 S % I I SOS 0) >> .tJ i ^ & ^ w .a I I b 5- a 'S fc fe II b| -s3 | s It ^ - j; _. o ^8 E ^ O *rt o 5* S *o o'^'aj'^ "S ^ S O w W WZ Oo eq DH Q OS 6 I 1 i I i I s js (2 ^ ilia 1 1- S >> o 6 ^ *> >> .B w-M >> ^ rt J43 S c 3 O, 1^-S W '^ W j c a w PQ w coZ IGNEOUS ROCKS (CHIEFLY GRANITES) AND GNEISSES 135 :g Si ON :o m S 6 > 43 I 3 a T3 5 2 X jy} -S .S tj .03 .2 -2 -S ^ .3 S-S K: 43s : ..Sa : M 8-.2 : ^^Sl i ^.S'32 : 42 5 S a3 ^-' 6 . S &>2 K! >, O43 M J ^ii!l 5 : g^si^a 7 37 C 0.24 < o 56 2.12 o 50 I. 3 o. 19 Water (H 2 O) ) I.: 2.00 0.61 1 As carbonates. I. Portland, Conn.; II. Berea, Ohio; III. Port Wing, Wis.; IV. Warrens- burg, Mo.; V. Warsaw, N. Y.; VI. Hummelstown, Pa. SANDSTONES 165 Weathering Qualities. Sandstones, as a rule, show good dura- bility. Some of the softer ones may disintegrate under frost action. Those with clay seams are liable to split with continued freezing. Mica scales, if abundant along the bedding planes, are also likely to cause trouble, and this is aggravated if the stone is set on edge instead of on bed. A striking example of this is the Connecticut brownstone so extensively used in former years for fronts in many of the eastern cities. In order to get a smooth surface it was rubbed parallel with the bedding, and the stone set in the building on edge. The result is that hundreds of buildings put up more than 'fifteen or twenty years ago are scaling badly, and in many cases the entire front has been redressed. Sandstones sometimes change from gray to buff or brown on exposure to the weather due to the oxidation of the iron, but this does not necessarily indicate deterioration of the stone. Fire Resistance. Sandstones are perhaps as little affected by a heat of 1500 F. as any building stones, but are likely to spall and crack when exposed to the combined effects of fire and water. Some show a tendency to split along the bedding planes. VARIETIES OF SANDSTONE. The following variety names are based on difference in color, mineral composition and texture. Arkose. A sandstone composed chiefly of feldspar grains. Some is quarried in New Jersey. Bluestone. The name belongs properly perhaps to a flagstone much quarried in eastern New York. It is also used for bluish gray sandstones quarried at other points, as, for example, the Warsaw bluestone of western New York. Brownstone. A term formerly applied to sandstones of brown color, obtained from the Triassic formation of the Connecticut Valley of Connecticut and Massachusetts, and in other eastern states, but since stones of other colors are found in the same formation, the term has come to have a geographic meaning and no longer refers to any specific physical character. Calcareous Sandstone. One in which carbonate of lime forms the cementing material. 1 66 BUILDING STONES AND CLAY-PRODUCTS Ferruginous Sandstone. One containing considerable iron oxide in the cement. Flagstone. A thinly bedded, argillaceous sandstone used chiefly for paving or flagging purposes. Freestone. A sandstone which splits freely and dresses easily. Graywacke. A hard sandstone of compact character, com- posed of grains of quartz, feldspar, slate and perhaps other minerals, with a clayey cement. Quartzite. A very hard, usually very dense sandstone, which owes its hardness to pressure, or more commonly deposition of silica around the grains. Distribution of Sandstones and Quartzites. Sandstones and quartzites are widely distributed in the United States; indeed, so much so that there are numerous small quarries opened up in many states to supply a local demand. In a few cases, certain areas have been worked on a large scale to supply a wide extent of territory. This is true of the Con- necticut brownstone, so much worked in former years, and of the Berea sandstone of Ohio, which is extensively used now in the eastern and central, and, to not a small extent, in the western states. In view of this wide distribution of sandstone, it becomes some- what difficult to pick out a few prominent areas. NEW ENGLAND STATES. Sandstones are of little importance in most parts of New England. The best known is that of the Triassic formation of Connecti- cut and Massachusetts, which has been widely used in former years. This is a rather fine-grained sandstone, usually of reddish brown color, moderate density, and not extra hard. It lies in horizontal beds which vary from a few inches to twenty feet in thickness (Merrill). On account of the large amount of quarry water which it contains it cannot be quarried in freezing weather; indeed, Merrill states that a temperature of 22 F. is sufficient to freeze and burst blocks of the freshly quarried material; but a SANDSTONES 167 week or ten days of good drying weather is considered enough to protect the stone against frost. The fact that the stone splits under frost action when set on edge instead of on bed has somewhat injured its reputation. A brick-red variety of fine uniform grain is quarried at Kibbe, and East Longmeadow, Mass. The Connecticut brownstone has been extensively used in the eastern cities for constructional work, and especially as veneer blocks over brick for the fronts of buildings. It has also been much employed in former years for headstones in cemeteries. The Kibbe rock has found similar applications. Examples. Academy of Design, Brooklyn, N. Y.; Wesleyan University Buildings, Middletown, Conn.; Holy Trinity Episcopal Church, New York City; Court House and Post Office, Rochester, N. Y. ; lower stories of Waldorf-Astoria Hotel, New York City; Marshall-Field Building, Chicago, 111. (Kibbe sandstone above basement); Trinity Church, Boston, Mass.; Library and Stock Building, Princeton University, Princeton, N. J. ; numerous private residences in Boston, New York, Philadelphia and other eastern cities. EASTERN ATLANTIC STATES. These contain an abundance of sandstone suitable for building purposes. They may be briefly summarized as follows: NEW YORK. Medina Sandstone. A moderately fine-grained sandstone of light gray (called white) or red color and quarried chiefly be- tween Rochester and Lockport. The red is used chiefly for building purposes, and has a bright color. The gray may be used with it, but its main use is for paving blocks. Both types are stones of good durability and low absorption. Potsdam Sandstone. This is essentially a quartzite, usually very hard, dense, moderately fine-grained, and of red or reddish brown color. It is perhaps less used now than formerly. Its main occurrence is in northwestern New York, but it is also found in the east along Lake Champlain. Examples. Many buildings in Potsdam, N. Y.; All Saints Cathedral in Al- bany, N.Y.; parts of the Dominion Houses of Parliament, Ottawa, Canada. 1 68 BUILDING STONES AND CLAY-PRODUCTS Warsaw Bluestone. A fine-grained bluish gray sandstone of earthy appearance, much used for constructional work, but especially for trimmings in many of the eastern cities. Examples. University Avenue M. E. Church, Syracuse, N. Y.; Genesee Street Baptist Church, Rochester, N. Y. Hudson River Bluestone. The typical bluestone is a fine- grained, compact, tough sandstone, of blue-gray color, which breaks up readily into slabs a few inches thick, and sometimes of large size. On this account it has been extensively used for flagging, curbs, sills, steps, etc. It is quarried chiefly in Albany, Green and Ulster Counties. Some slabs of large size have been extracted. NEW JERSEY. Sandstones occur in many parts of the state. Lewis enumerates : 1. Brown sandstone, or brownstone, and also gray and white sandstones abundant in Triassic belt across central part of state. The white and gray occur at many points from the Delaware to the Hudson and are much used. They consist of quartz or quartz and feldspar. 2. Conglomerates and sandstones of Kittatinny Mountain region, southwest of Greenwood Lake. 3. White to gray sandstone or quartzite in northwestern counties. 4. Reddish, purplish and bluish gray argillites around Prince- ton, Lawrence ville and Byram. 5. Flagstones of Hunterdon, Warren and Sussex counties. Of these the first has been most important, but the demand is less than formerly. Much of that cut below water level hardens as the stone dries out. The localities of production include Chester, Ridgefield, Watchung, Martinsville, Princeton, Wil- burtha, Stockton. Brownstone is also quarried at several points, including Little Falls, Paterson, Belleville, etc. Examples. Trinity Church, N. Y.; Queen's Building, Rutgers College, New Brunswick, N. J. ; Old Court House, Newark, N. J. SANDSTONES 169 PENNSYLVANIA. The Triassic sandstone formation crosses Pennsylvania from New Jersey to Maryland, the chief quarries being at Hummels- town, Dauphin County. The rock obtained there is evenly bedded, fine grained and takes a smooth finish. Two shades are quarried, the most abundant being of a dark reddish brown color, resembling the sandstone from East Longmeadow, Mass. ; the other is a purplish brown. The stone is practically free from mica and has not been observed to scale off. The Hummelstown stone has been widely used. Examples. The Market and Fulton National Bank, New York City; Salem Lutheran Church, Lebanon, Pa.; High School, Altoona, Pa.; Presbyterian Church, Indiana, Pa.; Emory Methodist Episcopal Church, Pittsburg, Pa.; Union Station, Indianapolis, Ind. In western Pennsylvania, there are numerous sandstones in the Coal Measures formations, but they are little used except for local purposes. Near Pittsburg there are many quarries which produce small quantities of stone, and not a few of these are said to weather unevenly, owing to presence of calcareous matter, and are sensi- tive to frost. The Wyoming County stone, known to the trade as Wyoming Valley stone, is said to resemble the New York bluestone. MARYLAND. There is only one sandstone within the state which has at- tained any reputation as a building stone and that is the so-called Triassic or "Seneca Red." There are other sandstone areas in other parts of the state, but they are quarried only for local use. The Seneca red stone is from the same formation that supplies the brownstone of Portland, Conn., and that of Hummels- town, Pa. The prominent quarries are situated near the mouth of Seneca Creek, Montgomery County. The stone occurs in workable beds varying in thickness from 18 inches to 6 or 7 feet, and these are separated from each other by bands of inferior material of different color and texture. The sandstone beds, 170 BUILDING STONES AND CLAY-PRODUCTS themselves, differ very much not only in color but also in hard- ness and texture. The texture of the stone placed on the market is fine grained and uniform, not at all shaly, and shows little or no tendency to scale when exposed to the weather. It is said to be soft enough to carve and chisel readily when quarried, but after exposure becomes hard enough to turn the edge of well-tempered tools. Its color varies from an even, light reddish brown or cinnamon to a chocolate or deep purple brown. It is brighter when first quarried. Matthews gives several instances of the use of this stone which show its durability. The Smithsonian Institute, erected between 1848-1854, shows few defects from weathering alone. VIRGINIA. This state contains a number of sandstone formations, but none are worked for any except local use. WEST VIRGINIA. There are a number of sandstones in this state but they are mainly of local value. ALABAMA. In the Coal Measures area of the state, sandstones have been worked at Jasper and Cullman, and at Tuscaloosa. The locks on the Warrior River at the last-named place are constructed of this stone. The Hartselle (Lower Carboniferous) sandstone is quarried near Cherokee, Colbert County, and has been used for the locks at the Colbert Shoals on the Tennessee River. The Weisner sandstone has furnished the material for many buildings around Anniston. CENTRAL STATES. OHIO. There are several sandstone-producing formations in Ohio, but by far the most important is that known as the Berea sandstone or Berea grit. PLATE XXX. U. S. Post Office, Toledo, Ohio, constructed of Gay "Canyon" Berea sandstone. (Photo loaned by Cleveland Stone Co.) 171 SANDSTONES 173 This stone, which is widely used for building purposes, is of fine, even-grained texture, very light buff -gray color and evenly bedded. It is moderately porous and not extra hard, so that it can be easily carved and cut. In the best grades the sulphide of iron (pyrite) is finely divided and evenly distributed, and on exposure to the air the stone turns yellowish. This, however, does not seem to affect the durability or appearance of the stone. If the pyrite is unevenly distributed the stone has a blotched appearance, and such pieces are undesirable. The principal quarries are located in the town of Amherst, Berea and East Cleveland. Examples. Almost every large city contains structures of Berea sandstone. Among these maybe mentioned: Soldiers and Sailors Memorial Hall, Pittsburg, Pa.; Goldwin Smith Hall, Cornell University, Ithaca, N. Y.; Wayne County Court House, Detroit, Mich.; City Hall, St. Louis, Mo.; U. S. Post Office and Court House, Minneapolis, Minn. A stone known as the Euclid bluestone is obtained in Euclid and Newburgh in Cuyahoga County. It differs from the Berea in being finer grained and of a blue-gray color. Like the Berea it contains much pyrite, but does not weather uniformly, becom- ing blotchy. Its chief use is for bridge work, foundations and nagging. INDIANA. Sandstones of good quality are known in the Coal Measures formations of western Indiana, but the production is exceedingly small. Three may be mentioned. The Mansfield sandstone lies at the base of the Coal Measures and outcrops in a band 2 to 20 miles wide and 175 miles long, extending southeast from the northern part of Warren County. It consists of quartz grains with iron oxide cement, the color sometimes being dark brown, but more often buff or gray. The former (brown) is extensively used for trimming, while the latter is quarried for local use. The Knobstone sandstone is a fine-grained, light blue or drab- colored rock, well adapted to smooth finish or fine carving. It 174 BUILDING STONES AND CLAY-PRODUCTS is quarried somewhat extensively in Fountain County, but is not very durable unless carefully selected and set. The Coal Measures sandstone is finer grained than the Mans- field, buff, blue or gray in color, and very durable. It is said to weather to a rusty yellow not very pleasing to the eye. This rock has been quarried in some quantity at Worthy, Vermillion County, and Cannelton, Perry County. ILLINOIS. Sandstones are quarried in Henry, St. Clair and Carroll counties. MICHIGAN. The Potsdam formation outcropping on the Upper Peninsula is the most important source of sandstone in this state. That quarried at Marquette is a moderately fine-grained sandstone, of brownish red color, often spotted with gray. The gray spots as well as the occasional presence of clay holes and flint pebbles make a careful selection of the stone necessary. At Jacobsville, on Keweenaw Bay, the same formation sup- plies a stone of uniform, bright red color, even structure and texture, which has been much used for general building purposes and trimming. It is very porous, but seems to stand the weather well. The basement of the Cornell University Library is con- structed of it, and after twenty years of exposure to a severe climate shows no ill effects. Sandstones for local use are quarried in the Coal Measures formation of Southern Michigan. WISCONSIN. One of the most widely distributed sandstones and one which has furnished the greatest variety in color and texture is the sand- stone of the Potsdam and St. Peter's formations. The Potsdam sandstone forms a curved belt extending from the northeastern part of the state near Menominee, southwest- ward and then northwestward to the St. Croix River. In this belt the stone is quarried, among other points, at Dunn- ville. The sandstone in general is a very light buff, although some of the beds are more of a gray or bluish white. The texture SANDSTONES 175 varies from fine to coarse, and when first quarried the stone cuts easily and carves well. This stone is a good example of one, containing a very high amount of quarry water. Examples. Mabel Taintor Memorial Building, Menominee, Wis. ; Masonic Temple, St. Paul, Minn.; Pierce County Court House, Ellsworth, Wis. A second, but narrow, belt skirts the south shore of Lake Superior. The latter area is known as the Lake Superior sandstone, while the large belt is known as the southern Potsdam sandstone. The northern belt supplies a brownstone and is quarried around Bayfield and Washburn. The stone is of a brown-red color, fine grained, not easily injured by frost, and of good fire resistance. No trouble is experienced in getting rocks of large dimensions. Some beds show clay holes, others whitish discolorations, and still others are of pebbly character, but these can be avoided in quarrying. Several possible causes have, perhaps, reacted against the in- dustry, viz., fashion, improper use of brownstone, and shipment of inferior stock. The stone must not be quarried in freezing weather. Examples of Lake Superior brownstone: Court House, Milwaukee, Wis.; Central High School, Duluth, Minn.; Court House, Washburn, Wis.; Law Build- ing, Winnipeg, Man.; Walnut Street Opera House, Cincinnati, Ohio; Tribune Office Building, Chicago, 111. The St. Peter's formation forms a narrow strip, extending from the Menominee River, in a southerly and westerly direction. It is white, brown, red or yellow; medium and coarse grained, and not always hard. MINNESOTA. Large sandstone quarries are in operation at Sandstone on the Kettle River. The rock is a fine-grained, light pink stone, said to be hard and durable. Only about 20 feet of the 80 foot face are selected for choice building stone, and much of the upper courses is used for paving blocks and heavy masonry. Blocks 5 to 10 feet long can be easily obtained. The approximate prices of this stone are: Rock-faced dimen- sion stone, $i to $1.25 per cubic foot, f.o.b.; sandstone, two sides, 50 cents per cubic foot; paving blocks, $1.50 per cubic yard. 176 BUILDING STONES AND CLAY-PRODUCTS This stone is extensively used for building purposes in the Mississippi Valley states and makes a good structural material. Examples. Library Building, University of Illinois; United Presbyterian Church (interior), Worcester, Mass.; Spokane Club Building, Spokane, Wash.; Des Moines, la., Public Library. A good quality of quartzite is extensively quarried at New Ulm and makes a satisfactory building material. MISSOURI. The most important sandstone quarries in the state are located at Warrensburg and Miami. The formation supplies large blocks of sandstone of either blue or white color. Some of the stone is reedy and hence care is required in selecting it. The stone hardens on exposure to the atmosphere. ARKANSAS. This state is not important as a producer of sandstone but the northern part of the state, according to Branner (Stone, October, 1889), is said to contain a great quantity of cream-colored cal- ciferous sandstone which, on account of its color, firmness and massiveness, makes it desirable for architectural purposes. Gray sandstones come from coal regions of the state but are not used to any great extent. WESTERN STATES. MONTANA. Sandstone is quarried in between twelve and fifteen counties in the state, but the quarries near Columbus, Yellowstone County, are by far the most important. This locality supplies a sandstone of bluish color, fine grain, and unusually even texture, the latter reminding one somewhat of the Berea stone. The stone at times shows a cross-bedded structure. Example. Capitol at Helena, Mont. COLORADO. A number of good sandstones are found in this state, but owing to small demand and poor transportation facilities they are little used. The most important ones are the so-called red beds which are found at a number of points in the state. A belt SANDSTONES 177 of these extends along the foothills of the mountains, passing through Manitou and Boulder. This formation supplies a variety of stone, including a bright red stone which is often used for structural purposes and white, hard sandstone and also some softer sandstone. Many of these are not very durable. The first of these is known as the Manitou stone because it is quarried largely near that place. This stone works very easily and has been much used in public and private buildings in Denver. The harder type of sandstone, from the Red Beds, which is said by Merrill to be used for flagging and foundation, has been quarried at Bellvue, Stout and Arkins in Larimer County; at Lyons, Boulder and at other points in the foothills. This stone is a deep red color. A light-colored sandstone, some- what resembling the Berea sandstone, has been quarried near Canyon City and was used in the construction of the Court House at Denver. WASHINGTON. Sandstones are found at a number of points in the state, but the chief deposits occur on the western side of the Cascade Mountains. The Tenino stone is a fine-grained, dark-colored sandstone, with some mica, and hardens considerably after being quarried. Examples. High School Building, Seattle; Trinity Church, Seattle; Calvary Presbyterian Church, San Francisco, Cal. A blue-gray Carboniferous sandstone has been quarried near Bellingham. It is fine grained and somewhat harder than the Tenino sandstone. Examples. U. S. Custom House, Port Townsend; U. S. Custom House, Port- land, Ore.; Thurston County Court House, Olympia. CALIFORNIA. The most important sandstone-producing district of Cali- fornia is in Colusa County. Examples. Kohl Building, San Francisco; St. Francis Hotel, San Francisco; Jas. L. Flood Building, San Francisco. The Leland Stanford Buildings are constructed of sandstone from south of San Jose, Santa Clara County. It is buff and light gray. CHAPTER V. LIMESTONES AND MARBLES. LIMESTONES AND DOLOMITES. UNDER the name of limestone there is included a group of stratified rocks which consists essentially of calcium carbonate. They are sometimes quite impure, the common impurities, any or all of which may be present in varying amounts, being iron oxide, silica, clay and carbonaceous matter. Magnesia is likewise rarely absent, and with an increase of it the stone passes into a typical dolomite, which chemically consists of 54.35 per cent lime carbonate and 45.65 per cent magnesium carbonate. With an increase in silica the rock passes into a calcareous sandstone; with an increase of clay, into a calcareous shale. A limestone which has been rendered crystalline by meta- morphism is termed a marble, and this type is treated under a separate heading. It may also include some limestones of crystalline texture, which have not a metamorphic origin. These may be regarded as marbles in a commercial sense, but are not strictly so geologically. Color. Limestones show a great range of color, the most common shades being blue, gray, white and black, but other colors, due chiefly to iron compounds, may occur, although these more brilliant and beautiful colors are seen chiefly in the marbles. Hardness. Both calcite and dolomite are soft minerals, but the rocks of which they form the main constituent are often very hard. Limestones, however, as a class, show a great variation in their hardness. Some are so soft as to be readily cut with a saw, as, for example, coral rock, the Caen stone of France, and others. The Bedford limestone of Indiana is moderately hard, while the Shenandoah limestone of the southern states is a very firm rock. Texture. Most limestones are fine grained, indeed, so fine that the individual grains are not noticeable with the naked eye. 178 Plate XXXI, Fig. i. Limestone showing dark flint nodules. PLATE XXXI, Fig. 2. Tremolite in dolomitic marble. 179 LIMESTONES AND MARBLES l8l Some are moderately fine grained, as the oolitic limestones, while others are coarse grained, due largely to the presence of numerous fossils. The Coquina, found near St. Augustine, Fla., is to be classed with the last named. Absorption. The majority of the harder limestones have a very low absorption, usually under two per cent. Some widely used ones may run much higher. Thus the Bedford, Ind., limestone shows 4 or 5 per cent; the French Caen stone, 10 to 12 per cent; the Roman travertine still more. Weathering qualities. Both limestones and dolomites, if dense and massive, are moderately durable, though not to be compared with good sandstones or granites. Limestones weather primarily by solution ; that is to say, rain or surface water may slowly attack the rock, but the solution of the surface may go on very unevenly. If certain portions are silicified, such as fossils which have been replaced by silica, or if quartz veins are present in the rock, these resist the solvent action of surface waters more than the surrounding calcareous parts of the rock and are left standing out in relief, giving the stone a rough appearance. Dolomites do not weather so readily by solution, but dis- integrate, breaking off a grain at a time. This is specially noticeable in some coarse-grained ones, which have been exposed to the weather for from forty to fifty years. Pyrite is an undesirable mineral in either limestone or dolomite. Chert or flint should likewise be avoided. It sometimes' forms lines of concretions along the bedding planes and causes the stone to split when exposed to frost action. Crushing Strength. Most hard limestones show a good crush- ing strength, ranging from 9000 to 12,000 pounds per square inch. Fire Resistance. The resistance of limestone to fire, at tem- peratures below that required to convert the stone into quick- lime, is usually fair, although lime rock, like other kinds of stone, is apt to spall badly under the combined attack of fire and water. Tests of Limestone. There are few complete series of pub- lished tests, but the following table, though somewhat incom- plete, may serve to give some idea of their variation. 182 BUILDING STONES AND CLAY-PRODUCTS o r^ : : 1 ] fej 5- :& :S&2 :4 : :,g R^<5 ' ' ' i ' ro 10 ( 6 O r* CO 0* ... M IO o . r* . t** o* w w ^f'io*oo< v 5^tTf ^oo l> -NO -TTOONOO t> -NO -iOI>fOCOOvOswt^ . . i lit o ; ; : : ; i ; i ; i ; ; i : : : & $ ' ' ' : 8 : : '% ::::::: :$<% "& oo^ ( N | - tT tt^Or^c>c s iOLo ( N l o i o ' IOTTM MO ^tt^UOOOvO 1/>O t^ M O\ , 1 a 1 ! rt 4J 'S 2 2 'C Jj ^Srt^ rtsao'S O W PQUWW PQ ffi ^>-^OS O * f 00 t- y 8 II d d d d d : o M : : : : ^ 3 '^ > b _r :jj ;Z4. ^ o ,S T> ^ |8J3 2 |-|i ">-5 aJ-g c^ g^J SI^IIJIII '^* . > l| ! ^ 0) :^o 202 BUILDING STONES AND CLAY-PRODUCTS Among the other uses of marble are its application for wain- scoting and paneling, floor tiles, electrical switchboards and sanitary ware. If used for tiling floors it is often preferable to use but one kind, as marbles of different colors may be of unequal hardness, and hence a floor, over which there is much passing, may wear uneven in a comparatively short time. Many of the black and white tiled marble floors show this. The demand for marble tops for tables and washbasins is probably decreasing. Many beautiful decorative effects are produced by sawing a slab of colored or patterned marble in two or more slices and matching these together (Plate XXXV). Distribution of Marbles in the United States. Marbles are less widely distributed than limestones, since they occur almost exclusively in areas of metamorphic rock. Most of those quarried are white, few being of variegated color. Indeed, the larger part of the beautiful decorative ones with which most of us are familiar are imported from foreign countries. Vermont leads all other states in the quarrying of marble, but Georgia and Tennessee are also important producers. The more important occurrences are referred to below. VERMONT. The Vermont marble deposits begin on the south at Dorset Mountain and extend northward in a narrow belt through Wallingford, West Rutland, Pittsford and Brandon to Middle- bury. These are all true marbles or metamorphosed limestones. Another important locality has been opened up farther north at Swanton, but this is not a true marble. The marble used for building purposes varies from 75 cents to $2.00 per cubic foot, while that for monumental work may bring from $5 to $7, and statuary marble as much as $12. Those marbles quarried at Dorset are more coarsely crystal- line than those quarried in the West Rutland area. It can be said that in general the Vermont marbles usually show a bluish gray or whitish ground, the latter often showing a pinkish or creamy shade, and traversed by veins or markings, more or less distinct, of a green or brown color. fl !& .s.i h PH 203 N PLATE XXXVI, Fig. i. White marble, Vermont. PLATE XXXVI, Fig. 2. Gray marble, Vermont. (The color is due to carbonaceous matter.) 205 LIMESTONES AND MARBLES 207 Not infrequently several different varieties or shades are found in the same quarry. The following section brings this point out well, and shows the section found in the West Rutland quarries of the Vermont Marble Company. Blue marble, top ) 20 feet White marble f Green striped 2 feet. White statuary 5-6 feet. Striped monumental 2-6 feet. White statuary 3-6 feet. Layer partly green, partly white 4 feet. Green and white, " Brocadillo " 2^-3 feet. Crinkly, siliceous layer, half light, half dark 2-3 feet. Light and mottled 4-6 feet. Green striped 6 inches. White i\ inches. Half dark green, half white 3-6 inches. Italian blue 15-20 inches. Mottled limestone The following are varieties quarried in Vermont : LIGHT MARBLES. Best Light Cloud Rutland. Very light, mostly white, with very indistinct veinings, which show little, except on a polished sur- face. Quarried at West Rutland by Vermont Marble Company. Blue Building. A bluish gray stone, with whitish spots, and occasional white veins. Mainly for building, but also polishes. Quarried at Fowler by Rutland-Florence Marble Company. Brandon- Italian. Resembles ordinary veined imported Italian. General ground white, with indistinct dark bluish veins or lines or sometimes spots or blotches. Quarried by Brandon-Italian Marble Company. Brandon- Italian, High Street Variety. Similar to preceding, but usually darker. Quarried by same company. Brocadillo. Might be classed with fancy varieties. Re- sembles Listavena, but is darker and has greater abundance of green veins, which are sometimes very abundant and pro- nounced. Quarried at West Rutland by Vermont Marble Company. Dorset Dark Green Vein. Nearly white marble in some examples and greenish in others. White ground, cut by numer- ous green lines, veins, bands or blotches, so arranged that slabs 208 BUILDING STONES AND CLAY-PRODUCTS can be matched to form figures in a panel. There are also blotches. Examples. Interior paneling of Albany Commercial Bank; Four-piece panels, some of the latter being 18 feet high and 13 feet wide; Twenty-five columns in exhi- bition room of New York City Library; Interior of American Trust and Securities Building, Chicago. Dorset White. Appears pure white from distance, but upon close examination shows delicate light brown or smoky bands or veins. The Dorset marbles are harder and more coarsely crystalline than those of the Rutland district. Example. The New York Public Library Building on Fifth Avenue is built of this marble. Florence. For monuments and building. Bluish white ground clouded and veined with dark shades, varying from smoky to black. Quarried at Fowler by Rutland-Florence Marble Com- pany. Gray Building. General tone bluish gray, slightly mottled with white and veined with dark shades. Veins usually quite fine. Quarried at West Rutland by Vermont Marble Company. Italio. A moderately light marble, with bluish white ground, and darker bluish cloudings. Quarried at Columbian quarry, Proctor, by Vermont Marble Company. Light Florence. Resembles some of the light Italian marbles. Ground white with bluish cast, thickly clouded and streaked by dark spots and lines. Markings more regular than those of many Vermont marbles. Quarried at Fowler by the Rutland- Florence Marble Company. Light Green Cloud. A Dorset marble of clear white ground, with scattered greenish clouds and patches. Some of these are dark. A good building marble, but used especially in interiors. Quarried at Dorset by the Norcross-West Marble Company. Light Sutherland Falls. Nearly pure white ground, with veins, usually of a bluish white color. Quarried at Proctor. Listavena. Green and white bands. West Rutland. Mountain White. Very light, with occasional brownish veins. Quarried at Danby by Vermont Marble Company. Much has been used in New Senate Building in Washington, including sixty large columns. PLATE XXXVII, Fig. i. Quarries in Travertine near Tivoli, Italy. (Photo by J. C. Branner.) PLATE XXXVII, Fig. 2. Quarry of Vermont Marble Company, Proctor, Vt. (Photo loaned by Vermont Marble Company.) 209 PLATE XXXVIII. Kimball Monument, Chicago, 111. Done in Vermont white marble. (Photo loaned by Vermont Marble Company.) 211 LIMESTONES AND MARBLES 213 Pitts] 'or d- Italian. Light with yellowish brown lines. Quar- ried at Pittsford, by Rutland-Florence Marble Company. Pittsford Valley. First quality. Resembles Sutherland Falls. Plateau White. Very light with irregular creamy and greenish bands. A hard, durable marble. Example. New Harvard Medical Buildings. Quarried at Dorset by Norcross- West Marble Company. Statuary. A very white layer, quarried at West Rutland. DARK MARBLES. These include those in which black, dark green or blue pre- dominate over lighter shades or white. They are not so com- monly used for building stones as the lighter varieties, but are very effective when rock faced. Their main use would seem to be for interior finish. They are occasionally used for monuments. Some of the black ones are not true metamorphic limestones. Black or Fisk Black. This, properly, is a limestone. It is a dark gray or gray-black limestone. Not extensively used. Dark Florence. Bluish ground, with lighter veins. Quarried at Fowler, by Rutland-Florence Marble Company. Dark Vein Esperanza. One of the darker Vermont ones. West Rutland. Dark Vein or True Blue. West Rutland. Extra Dark, Mottled True Blue. Extra Dark, Royal Blue. Darkest marble found in Rutland area. Other varieties are: Extra Dark Vein True Blue; Florentine Blue; Highland Blue; Livido. ORNAMENTAL OR FANCY MARBLES. , Many of these are not as brightly colored as some of the imported ones, but they often show very decorative effects. Among them may be mentioned : Molian. American Pavonazzo. Dark green veins on a beautifully tinted creamy ground. Quarried at West Rutland by Vermont Marble Company. 214 BUILDING STONES AND CLAY-PRODUCTS American Yellow, Pavonazzo. Color mainly light salmon, with yellow or creamy tints. Quarried at West Rutland by Vermont Marble Company. Columbia Listavena. Light yellow ground, with veining of gray, light brown or olive. Quarried at West Rutland by Vermont Marble Company. Olivo. A Rutland marble similar to Brocadillo. Pink Listavena. Salmon ground, greenish veins. Rosaro. Light yellow with delicate light olive veins. Rubio. Delicate pink ground inclining to salmon, and in- definite veinings of light green. Quarried at West Rutland. Verdoso. A green- shaded West Rutland marble. Verdura. A greenish marble from West Rutland. Champlain Marbles. These are Lower Cambrian Red Sand- rock, being an unusually calcareous portion of the same, and grade into each other. With one exception they are all quarried at Swanton and by the Barney Marble Company. They all con- tain much silica and^iron and are predominantly shades of red and white. Being harder than marble, they take a more brilliant and durable polish. For the same reason they are more costly to saw and finish, but are used for flooring and wainscoting all over the United States. The varieties are Jasper, Lyonnaise, Olive, Royal Red and Oriental Verde. Examples of Vermont Marbles. The following list of buildings constructed wholly or in part of Vermont marble, have been supplied by several companies: Vermont Marble Co.: U. S. Post Office and Court House, Worcester, Mass.; Sutherland Falls marble; U. S. Post Office and Court House, Montpelier, Vt., the same; Hart Memorial Library, Troy, N. Y., Rutland white marble; Clio Hall, Princeton College, Princeton, N. J., Sutherland Falls marble; Second National Bank Building, Paterson, N. J., the same; Altar, Church of the Sacred Heart, Shelby, Ohio, Rutland white marble; Stock Exchange, Chicago, 111., restaurant and ceiling, Listavena and White; Columbia Bank, Pittsburg, Pa., all interior finish Brocadillo; Hibbs Building, Washington, D. C.; Planters Loan and Savings Bank, Augusta, Ga.; Interior marble, Office Building, House of Representatives, Washington, D. C.; Marble for Gardens, J. D. Rockefeller, Pocantico Hills, N. Y., Rutland-Florence Marble, Fowler, Vt. Brandon-Italian, Middlebury, Vt. : Exterior Memorial Church, Middlebury; Public School Building, Hudson, N. Y.; Annex to Fanny Allen Hospital, Burling- ton, Vt. This marble is used mainly for interior and vaults. LIMESTONES AND MARBLES 215 Examples of Cham plain Marbles. The following list is supplied by the company: Red marble: Government Building, Troy, N. Y.; Metropolitan Museum of Art, New York City; Government Building, Denver, Colo.; Congressional Library, Washington, D. C.; Planters Hotel, St. Louis, Mo.; Auditorium Hotel, Chicago, 111.; Union Station, Toronto, Canada. Red and green marble: Erie Savings Bank, Buffalo, N. Y.; Albany Savings Bank, Albany, N. Y.; Government Building, Omaha, Neb.; Philadelphia Mint, Philadelphia, Pa.; New St. Charles Hotel, New Orleans, La. Green marble: New Southern Terminal Station, Boston, Mass.; Hotel Raleigh, Washington, D. C.; Pittsburg and Lake Erie Depot, Pittsburg, Pa. MASSACHUSETTS. A rather fine-grained, snow-white marble has been quarried for a number of years at Lee in western Massachusetts. Its chief use is for structural work. Examples. Wings of Capitol, Washington, D. C.; Public Buildings, Phila- delphia, Pa.; Court House, Baltimore, Md.; Metropolitan Insurance Building and Clearing House, New York City; State House Annex and new Commonwealth Trust Co., Building, Boston, Mass.; Interior work, Gen. Grant's Tomb, and Plaza Hotel, New York City. CONNECTICUT. In northern Litchfield County, near East Canaan, a white, moderately coarse dolomite occurs, but it has been little worked in recent years. The stone weathers well, but, like the Lee (Mass.) dolomite, often contains crystals of tremolite. Example. The State House at Hartford, Conn. NEW YORK. Southeastern New York contains a number of beds of dolomite marble. This has been quarried at Tuckahoe, Pleasantville and South Dover. The Tuckahoe stone is moderately coarse grained and pure white, but turns grayish on exposure to the air, as the coarse- grained surface catches the dust. Examples. St. Patrick's Cathedral, New York City; Metropolitan Life In- surance Building, New York City. The South Dover marble is finer grained than the Tuckahoe, but also of white color. It has been used mainly for ordinary structural work. Examples. Tiffany Building, New York City; Essex County Court House, Newark, N. J. 2l6 BUILDING STONES AND CLAY-PRODUCTS A moderately coarse-grained, light gray, or grayish white dolomite marble is quarried near Gouverneur, St. Lawrence County. It is well adapted for ordinary structural work, and for inscriptional purposes shows a good contrast between the polished and hammered surface. Some dense limestones, susceptible of taking a good polish, have been quarried to a small extent in Clinton County, near Plattsburg and Chazy. 1 The one known as Lepanto marble is a fine-grained gray stone, with pink and white fossil remains. The other, known as French gray, is more uniformly gray and bears larger fossils. Both are quite ornamental, but their use has declined. A black limestone known as black marble has been quarried at Glens Falls. PENNSYLVANIA. A white dolomite marble of sugary texture is quarried at Avondale, Chester County. It is used for structural work. There are a number of occurrences of crystalline limestone in southeastern Pennsylvania, but few of them are worked for marble. MARYLAND. The two marble-producing localities are Cockeysville and Texas, and although they are quite close together the marbles differ from each other in purity and texture. The Texas stone is a coarse-grained, calcite marble and is not used now for building purposes, although some of it was quarried and placed in the lower 150 feet of the Washington monument. 2 The Cockeysville marble is a fine-grained dolomite, well adapted for building and decorative use. It is clear white in color with occasional streaks of pale gray, but care has to be used to avoid streaks of silicate minerals which occur here and there in the quarry. Examples. Washington Monument, Mt. Vernon Place, Baltimore, Md., erected in 1829; 108 monoliths, 26 feet long, for National Capitol; U. S. Post Office Building, Washington; Drexel and Penn Mutual Insurance Building, Philadelphia, Pa.; Spires of St. Patrick's Cathedral, New York City; Art Museum, Pan-American Exposition, Buffalo, N. Y. 1 Merrill, "Stones for Building and Decoration." 2 Ibid. LIMESTONES AND MARBLES 217 A curious stone is that known as the Calico marble, quar- ried at the Point of Rocks, Frederick County. It is a con- glomerate, made up of limestone pebbles which average two to three inches in diameter. The rounded and angular fragments are gray to dark blue in color. The pebbly character of the stone and irregularity in hardness make it difficult to polish and work. Example. Columns of this marble are in the old House of Representatives now used by the Supreme Court. VIRGINIA. While crystalline limestones occur in Virginia, still the state is of little importance as a marble producer. The principal localities found west of the Blue Ridge may be described as follows : New Market and Woodstock, A coarse-textured, dun-colored marble, capable of taking a good polish; New Market, A mottled bluish marble, somewhat coarser grained than preced- ing; Buchanan, Gray marble of fine gray character; Lex- ington, White, fine-grained marble, capable of taking a good polish; Giles County, Red marble; Blacksburg, Black, fine- grained marble, taking high polish; Rockingham County, shaded yellowish gray and slate-colored marble taking high polish. Only the last has been worked for commercial purposes. NORTH CAROLINA. A narrow strip of marble is found in Cherokee County, N. C., which is a continuation of the beds in Fannin County, Ga. The stone is medium to fine grained in texture, and of two distinct colors, viz., a blue gray more or less mottled and streaked with white, and almost pure white. The marble belt lies between schists and quartzites, and near its contact with these the marble is apt to contain tremolite, talc and quartz. The stone takes a good polish and shows good contrast be- tween polished and hammered surface. In Swain County there are beds of marble of varying colors, from gray to black, cream white and pink, various mixtures, and sometimes greenish. 2l8 BUILDING STONES AND CLAY-PRODUCTS TENNESSEE. The marbles of the valley region of east Tennessee are well known. They are moderately coarse grained, of variable color and often highly fossiliferous. The best-known variety is a fossiliferous dark chocolate rock, variegated with white. Much of the ornamental beauty of this stone is due to the patterning produced by the white fossils in the rock. In addition to the dark chocolate colored stone, there is a lighter colored gray and pink, variety which is extensively used for wainscoting. All the Tennessee marbles take a good, durable polish and cut to a sharp edge. They are used for paneling, wainscoting, furniture tops, switchboards, and, less often, monumental pur- poses. GEORGIA. The calcitic marbles thus far worked on a commercial scale occur along the Louisville and Nashville Railroad in the northern part of the state. The most important deposits being found in Pickens County. The stone is coarsely crystalline and often micaceous. The color is white, white with streaks or blotches of black, gray and pink colors. In some the banding is very pronounced, and highly ornamental matched slabs are produced. Among the varieties produced, the following may be mentioned : Cherokee, white calcite; Creole, black and white mottled, coarse grained, calcitic; Etowah, flesh colored, coarse grained, calcitic ; Southern, white with bluish gray markings ; Silver Gray Cherokee, bluish gray. The Georgia marbles have, in recent years, been extensively used for constructional and monumental work, some splendid pieces of work being seen at a number of points. The following may be mentioned among others. Examples. Minnesota State Capitol, St. Paul, Minn.; Rhode Island State Capitol, Providence, R. I.; Carnegie Public Library, Atlanta, Ga.; Facade of New York Stock Exchange, New York, N. Y.; The State Savings Bank, Detroit, Mich.; Corcoran Art Gallery, Washington, D. C.; Girard Trust and Banking Company, Philadelphia, Pa.; New Orleans Court House, New Orleans, La.; Royal Bank of Canada, Montreal, Can.; LaSalle Street Station, Chicago, 111.; Royal Insurance Building, San Francisco, Cal. "^" '~~^ >* s s-e 2IQ 221 LIMESTONES AND MARBLES 223 ALABAMA. According to Smith, true marbles occur mainly in a narrow valley along the western border of metamorphic rocks, extending from the northwestern part of Coosa County through Talladega into Calhoun. The best known are in Talladega County, and the principal quarries from which stone has been obtained are near Sylacauga and Taylor's mill. Some of the marble is fine grained and very white, closely resembling Carrara marble; other types are cream colored, clouded, or streaked with micaceous and talcose streaks. The last two are undesirable for exterior work. Some of the varieties are Pocahontas, Alabama sunset, Ala- bama iris, etc. Examples. In rotunda and other parts of main story of new Custom House, also in Night and Day Bank, New York City; National Metropolitan Bank, Washington, D. C.; exterior Maryland Institute, Baltimore, Md. MISSOURI. This state does not produce any true marble, but the dense, light cream white limestone quarried near Carthage is often classed as such in the trade. This stone takes a polish and might be classed as a monotone marble. Examples. Denkman Memorial Library at Rock Island, 111.; Court House, Butler, Mo.; for interior work of Masonic Temple, Wichita, Kan. COLORADO. Marble deposits have been opened up in recent years at the head of Yule Creek, Gunnison County. The stone is fine grained, and the following types are said to occur: (i) White statuary marble, pure white, very fine grained, and takes .good polish; (2) Streaked black and white with serpentine veins; (3) Blue-black, shading into blue-gray with blotches and veins of green serpentine; (4) Streaked, dark mottled, soft blue-gray to black with a few lines of jet black cut by green veinlets of ser- pentine; (5) Pale flesh, or pinkish chocolate, mottled and gen- erally light. ARIZONA. Some decorative marble has recently been quarried in Arizona. The varieties advertised are: Arizona Opal, white with creamy 224 BUILDING STONES AND CLAY-PRODUCTS yellow and pink, with light pink veins; Arizona Pavonazzo, strong creamy white and light pinkish tone with a few strong black veins ; Arizona Pavonazzo, heavy veins. CALIFORNIA. A dolomitic marble is quarried north of Keeler, Inyo County. The stone is generally tine grained and takes a good polish. Among the varieties are a white, mottled white, gray, yellow and black. The streaked grayish black and white has been much used for wainscoting. The black is used for flooring. CHAPTER VI. SLATE. ON an earlier page it was explained that slate is a metamorphic rock, having a more or less perfect cleavage, because of which it has a number of commercial uses. Slate is fine grained and varies in color from black or gray to red, green and purple. The lustre is usually dull, but some slate is quite lustrous. Slates are derived by metamorphism, chiefly from sedimentary rock (shales), and the classification of these is given by Dale as follows : (A) Clay Slates. Purple red of Penrhyn, Wales; black of Martinsburg, W. Va. (B) Mica Slates. (1) Fading: (a) Carbonaceous or graphitic (blackish). Lehigh and Northampton counties, Pa. ; Benson, Vt. (b) Chloritic (greenish). "Sea green," Vermont. (c) Hematitic and chloritic (purplish). Purplish of Pawlet and Poultney, Vt. (2) Unfading: (a) Graphitic. Peachbottom of Pa. and Md.; Arvonia, Va.; Northfield, Vt.; Brownville, Monson, Me.; North Blanchard, Me.; West Monson, Me. (b) Hematitic (reddish). Granville, Hampton, N. Y.; Polk County, Ark. (c) Chloritic (greenish). "Unfading green," Vermont. (d) Hematitic and chloritic (purplish). Purplish of Fairhaven, Vt. ; Thurston, Md. 225 226 BUILDING STONES AND CLAY-PRODUCTS In the clay slates the particles are merely compressed by weight or pressure and cemented by carbonates of lime and magnesia, by clay and iron oxide. Their cleavability, strength and elasticity are low. The mica slates have an abundance of mica scales developed by metamorphism and possess a high grade of fissility, strength and elasticity. There is, however, much variation in composition and struc- ture even within this second group the mica slates. Thus the amount of ferrous carbonate determines the liability to discolor on exposure to the atmosphere, those containing much being of a fading character. This gives us the division of fading and unfading slates. The slaty cleavage is an important property which has been already referred to. As a rule, it is not coincident with the bedding, but may form almost any angle with it. Repeated freezing and thawing has a disastrous effect on the cleavability of slates, and the material must be split when fresh from the quarry. Many slates show extremely fine plications on their cleavage surfaces, and to this the name of bate or false cleavage is given by the quarrymen. The slip cleavage consists of minute plications, which result in microscopic slips or faults along which the slate breaks easily. Grain is a direction along which the slate can be split, but not as smoothly as along the true cleavage. The grain is indicated by a somewhat obscure striation on the cleavage surface in a direction nearly parallel to the cleavage dip. Joints are found in all slate quarries and may traverse the slate in various directions. The term Post is applied to a mass of slate traversed by so many joints as to be useless. Ribbons are lines of bedding, or thin beds, which show on the cleavage surface and are often of a different color. If irregular and numerous, they may make the slate worthless, but in many cases do no harm. Veins of quartz or calcite occur in some quarries and render those portions of the slate in which they are found worthless. Pyrite in lumps or grains is equally injurious. PLATE XLI, Fig. i. Slate quarry, Penrhyn, Pa. (Photo by H. Ries.) PLATE XLI, Fig. 2. Splitting slate. (Photo by H. Ries.) 227 SLATE 22Q The chemical analysis of slate is of little value in most cases, except for purposes of scientific study, although those slates which are most likely to discolor seem to contain greater amounts of ferrous carbonate. PROPERTIES OF SLATE. The physical characters of slate are mostly so different from those of other building stones that a special series of tests is usually necessary. These properties and tests may be referred to separately. Sonorousness. If a good-sized piece of roofing slate of the usual thinness is suspended and struck with some hard object it will emit a ring like semi- vitreous china. Mica slates are more sonorous than clay slates, but those with considerable chlorite may be deficient in this respect. Cleavability. The slate is split with a thin chisel about two inches wide, in order to determine the smoothness, thinness and regularity with which it cleaves. Cross Fracture (Sculping). This property, which should be tested by an experienced person, is to determine the character of the grain. Character of Cleavage Surface. It should be noted whether or not the slate cleaves smoothly. Lime. A drop of cold, dilute muriatic acid applied to the edges of a freshly quarried slate will, by the effervescence, indi- cate the presence of lime. Slates containing a large amount of lime carbonate are more likely to be acted upon by acids in the atmosphere. Color and Discoloration, The value of a roofing slate depends somewhat upon its permanence of color. To obtain informa- tion on this point the fresh slate should be compared with pieces which have lain on the dump for several years, or pieces on the roof. Presence of Clay. If much is present, the slate will emit an argillaceous odor when breathed upon, but the very best slates do not. 230 BUILDING STONES AND CLAY-PRODUCTS Presence of Marcasite. Good slates should be free from this form of iron sulphide, which is recognized by its yellowish color and metallic lustre. The objection to it is that it decomposes to limonite. Strength. The transverse strength of slate is of importance and should be determined. In the best slates the modulus of rupture should range from 7000 to 10,000 pounds. An impact test devised by Merriman is as follows : A wooden ball weighing 15.7 ounces is allowed to fall 9 inches upon a piece of slate 6 by 7! inches and 0.20 to 0.28 inch thick, the blows being repeated until the slate breaks. The foot-pounds of work per pound of slate can be calculated from the weight and thickness of the slate and the number of blows. Toughness or Elasticity. If a slab of slate is fastened between two supports and subjected to pressure it will bend slightly before breaking. The deflection of certain Pennsylvania slates, when placed on supports 2 2 inches apart, amounts to 0.27 to 0.313 inch (Merriman) . Density or Specific Gravity. This averages about 2.75, and is affected by the amount of magnetite or pyrite present. Abrasive Resistance. This is of importance where the slate is used in thick slabs for stair treads. There is no standard method of determining it. Corrodibility. Slates should resist exposure to an acid atmos- phere. They may be exposed to it in two ways, either by moisture or rain water with acid flowing on the upper surface, or by the capillary creeping up of such water between the slate slabs on the roof. A method of testing this resistance consists in using a solution consisting of 98 parts of water, i part of hydrochloric acid and i part sulphuric acid. A weighed piece of slate 3 by 4 inches .was immersed in this for 120 hours, then dried for 40 hours, weighed, the solution strengthened, and the piece reimmersed for another 120 hours, and weighed again. The losses in tests made by Merriman range from o to 2.76 per cent. Electrical Resistance. If a slate is to be used for electrical switchboards this should be determined. SLATE 231 According to the Electrical Engineers' Standard Handbook the resistance of slate runs about 78,000 megohms per centimeter cube. This is considerably higher than marble, which runs from 435 to 510 megohms per centimeter cube. Slate, however, is not as desirable as marble for switchboards for the reason that it is likely to have veinlets of metallic minerals, which sometimes cause a short circuiting of the current, and it is therefore used much less now than formerly. Published data of such tests are rare even if they have been made. Some tests of this character have been carried out on red slate from Slatington, Ark., by Professor W. M. Gladson, 1 whose description follows: " These pieces of slate were tested in comparison with three pieces of gray slate taken at random from old switch bases in the University electric laboratory. A piece i centimeter cube Guard wire Fig. 4. Diagram showing electric connections made in testing slate. was cut from each sample, and these were numbered consecutively from i to 9, Nos. i, 3 and 4, being gray slate. In preparing the cubes metallic particles were found in samples 4 and 6, and Nos. 5 and 6 were so easily split that it was difficult to obtain a centi- meter cube. "The pieces of red slate as received were smooth blocks, 4 by 5 inches by f of an inch, neither varnished nor in any way filled. They were red or reddish-brown, were much softer than the gray slate, and split much more readily. All samples tested 1 U. S. Geol. Surv., Bull. 430 F, p. 57. 232 BUILDING STONES AND CLAY-PRODUCTS were dry and appeared to be seasoned. The method of measur- ing the resistance of these centimeter cubes was as follows : "A block of paraffin wax was attached to the center of a glass plate, which in turn was thoroughly insulated from the table by glass strips piled across one another. In the top of the paraffin block an opening was cut i centimeter square and about 3 milli- meters deep. In the bottom of the cavity thus formed, four copper supports were embedded so that their top surfaces were in the same plane, about i millimeter below the top of the paraffin cup. A drop of mercury coming about flush with the copper supports in this cavity formed one terminal for making electric connection to the slate cube. Contact with the opposite face was made by placing a well-amalgamated zinc plate i centimeter square on top of the cube. This arrangement insured equal contact with each slate cube under test. "The galvanometer used was of the D' Arson val type, and had a working constant of 70,533 millimeters on the scale i meter distant through i megohm resistance. The electromotive force was furnished by storage cells and was kept constant at 42 volts during the experiment. "The connections were made as shown in the figure. "To avoid leakage over the surface of the slate a guard wire was connected as shown. All readings were taken after the deflections became constant; in some cases they did not become so until half an hour after electrification. "The results of the test are shown in the following table, from which we find the average resistance of all samples to be 1224.2 megohms per cubic centimeter. The average resistance of the three gray samples was 1180, and of the six red-slate samples 1267.8 megohms per cubic centimeter. Each piece tested, except No. 7, shows a different resistance between each pair of opposite parallel faces, which seems to depend on the plane of cleavage. The gray-slate samples show a decidedly higher resistance between faces of cubes perpendicular to cleav- age planes, but in individual samples the distribution of re- sistance would be greatly affected by the presence of foreign conducting particles or seams, which are likely to be present in all slate." The results of these tests are considerably lower than the figures quoted from the Electrical Engineers' Standard Hand- book, and given on page 236. SLATE 233 RESULTS OF TESTS OF ELECTRIC RESISTANCE OF SLATE SAMPLES. Sample number. Galvanometer scale deflections. Resistance.* Perpen- dicular to cleavage planes. Parallel to cleavage planes. Perpen- dicular to cleavage planes. Parallel to cleavage " planes. D D' D" R R' R" I 2 mm. 39-0 98.0 171.0 35-o 104.0 338.9 91 .0 57-o 45-o mm. 40.0 174.0 185.0 94.0 47-7 28.0 91 .0 5 1 - 33-0 mm. 44-0 625.0 283.0 43-0 39-9 88.0 48.0 27.0 36.0 Megohms 1808.5 719.7 414.9 2015.3 678.2 208. 1 775-0 1500.7 1567-4 Megohms 1763.3 405.3 381.2 750.4 1476.3 2519.0 775-0 1383 2137-3 Megohms 1603.0 6 7 .I 249.2 1640.3 1767.1 801.5 1469.4 2612.3 1959-2 3 4 cr 6 7 8 g * R, R' and R" correspond to the directions D, D' and D", respectively. Average of Nos. i, 3 and 4 (gray slate) 1 180.6 megohms per centimeter cube. Average of Nos. 2, 5, 6, 7, 8 and 9 (red slate) 1267.8 megohms per centi- meter cube. Average of all samples, 1224.2 megohms per centimeter cube. Tests of Slates. The following tables, taken from the work of Dale and Purdue, include a number of tests that have been made of different kinds of slate. TESTS ON ARKANSAS SLATE. Modulus of rup- ture, Ibs. per sq. in Modulus of elasticity. Specific gravity. Per cent absorp- tion, 24 hrs. Color and quarry. Max. Aver. Max. Aver. Max. Aver. Max. Aver. Red; Southwestern Slate Co 6,060 4450 4,640,000 3,660,000 2.86 2.86 0.018 0.017 Green; Southwest- ern Slate Co 6,840 6620 6,430,000 5,980,000 2.81 2.81 0.008 0.008 Black; M. J. Har- rington 9,640 8040 13,420,000 11,05)0,000 2.70 2.69 0.016 0.014 Reddish brown; M. W. Jones. . . 12,590 9600 19,530,000 16,340,000 2.84 2.84 o.oo3 0.007 Buff"; C. B. Baker. 4,150 3720 6,090,000 5,100,000 2.83 2.82 0.018 0.015 Quoted from report by Purdue, Ark. Geol. Surv. 234 BUILDING STONES AND CLAY-PRODUCTS >> 6 u ooooooooo OOOOOOwOO ooooooooo 666666666 ooooooooo t^ I s - r- r- t^ r- r- . ^^_ _ " -. * ^ "' x P ^ ^^ , _ _^" _^ " "*" -^ ^_ _^ ,~~ - 112 - ~ . 82 ^' " ^. .^ Fig. 10. Diagram showing absorption tests on Wisconsin soft-mud brick after 290 forty-eight hours immersion. Lbs. 8000 7500 7000 6500 6000 5000 4500 3000 1500 1000 Fig. ii. Diagram of crushing and transverse tests on Wisconsin stiff-mud brick, (After Ries, Wis. Geol. Surv., Bull. XV.) 291 2Q2 BUILDING STONES AND CLAY-PRODUCTS greater strength along one plane than another. Auger lamina- tions may be regarded as influencing abnormal structure. As a matter of fact, clay products are never taxed beyond their compressive strength. 00 , 1 \ 1 \ 1 \ \ 1 \ \ 1 \ j 1 1 1 \ \ J I ' \ ^ / \ 1 j / \ / \ 1 1 I i \ / \ 1 1 \ i \ / \ \ / 1 \ , i \ / j / i 1 I i \ i t 1 I \ \ 1 i 1 1 ! ] 1 1 \ \ 1 1 \ 1 \ \ / V 1 / \ i 1 \ \ 1 \ \ / \ t i \ i \ \ 1 \ 1 i 1 \ 1 \ 1 \ 1 \ l 1 \ I 1 ! g 'c 1 i 8 I \ \ r, i \ i I s s 1 1 5 : t S f, g r t \ 3 I t I ^ : I i I c 2 * t! 5 $ a - \ 1 1 g I Fig. 12. Diagram showing absorption tests on Wisconsin stiff-mud brick after forty-eight hours immersion. In testing the crushing strength of a brick, the latter is usually laid flatwise. Some objection has been raised to this on the ground that there is a large experimental error due to shape. BUILDING BRICKS 293 Theoretically, the best form of test piece is that of a cube, or still better a prism of square cross section, the height of which Ijhs . is i^ times the breadth, as this gives sym- metrical fracture planes. A custom followed in Germany is to use two half bricks cemented together by a thin joint of Portland cement mortar. This gives a prism and yields satisfactory results. An advantage claimed for testing a brick on edge is that the failing point can be more sharply detected than when the brick is tested flatwise. One objection to testing brick on edge is that it does not represent the position of the brick when in use ; however, this is un- important, since the compression strength per se has no practical value, except in so far as it differenti- ates between good and poor materi- als. But since the flatwise test is liable to serious errors, it is clear that the advan- tage must lie with the edgewise method which af- fords more reliable 1Fig 13b comparative data. Fig. 13. (a) Diagram of crushing and transverse tests on Wisconsin dry-pressed brick. The upper end of each line represents the crushing strength and the lower end the modulus of rupture. (6) Absorption tests of same series. (After Ries, Wis. Geol. Surv., Bull. XV.) euuu 5000 4301) 1000 3500 3000 2500 1500 i ' j ' j Pei- Cent 30 25 20 15 m i j i i i L f \ i / \ ; \ i / \ 2 \ / / 1 \ 1 1 \ 1 1 \ 1 \ \ / "Fig. 13a. 294 BUILDING STONES AND CLAY-PRODUCTS It is not possible to calculate from the strength on edge what it will be when the brick is tested flatwise, or vice versa, except for one and the same brick, since the structure plays such an important role. It is said that a side-cut brick will show a different com- pressive strength, when tested on edge, from an end-cut one made from the same clay. The following table taken from the War Department's report on Tests of Metals, etc., for 1895, shows that the compressive strength of a wet brick is usually lower than that of a dry one. COMPRESSIVE STRENGTH OF WET AND DRY HALVES OP THE SAME BRICK. Manufacturers. Description. Compressive strength per square inch. Dry. Wet. Loss. Gay Head Clay & Brick Co., Chelsea, Mass New England Steam Brick Co., Prov idence, R. I. ... Buff Buff... Pounds. 5,774 5,570 6,481 2,639 5,777 7,888 10,624 11,353 5,6oi 9,655 3,599 10,712 4,929 16,019 4,447 15,842 2,414 11,942 18,072 12,000 16,018 7,724 2,973 Pounds. 4,900 5,346 5,063 2,321 4,5o6 8,917 10,482 8,088 4,530 6,230 3,289 9,902 4,142 14,822 4,052 11,273 1,885 7,941 11,911 12,652 15,611 7,037 2,778 Pounds. 874 244 1418 318 1271 1029 142 3265 1071 3425 3io 810 787 1197 395 4569 529 4001 6161 -652 407 687 195 Buff speckled Firebrick Red No. I.. Red, No. 2.... Red, No. 3.. Red No. 4.. Light hard, water struck . Hard body Light buff, No. 55 Paving : Cream white, No. I Light red. No. 3 Cream white, No. 4 ( Vitrified paving, A \ Fire, No. i Vitrified paving block . . . f Red, No. i ( Red, No. 2.. The Powhatan Clay Manufacturing Co., Richmond, Va The Coaldale Brick & Tile Co., Coal- dale, Ala The A. O. Jones Brick & Terra Cotta Co Zanesville O. Kansas City Hydraulic Press Brick Co. Kansas City, Mo. . . Monticello Brick Works, Monticello, Minn A. Humphrey, Minneapolis, Minn Pacific Clay Manufacturing Co., Los Angeles, Cal Mean Relative strength, per cent . . . Face, No. 2 Light chocolate, No. 71 . . 8,039 100 6,835 85 1204 15 Transverse Test. This is a more important test even than the crushing strength, for, while the brick is rarely loaded up to its crushing limit, it is sometimes exposed to its limit of elasticity and cracked. This can, perhaps, be better understood if the manner of making the test is first explained. BUILDING BRICKS 295 In the cross-breaking test a whole brick is placed on two rounded knife-edge bearings. Pressure is applied from above, at a point midway between the two supports, until the brick breaks in two, and the number of pounds at which this occurs is noted. It is evident that in two bricks of exactly the same degree of strength, the amount of pressure necessary to break them will depend upon (i) the distance between the supports and (2) the cross section of the brick. The farther apart the supports the less pressure necessary to break the brick, and the greater the cross section the greater the pressure necessary. Since this is so, it is necessary that for purposes of com- parison all results of the breaking strength be reduced to some uniform expression which shall take account of the differences in length, width and thickness of the brick. The most accurate expression is that termed the modulus of rupture, which is calculated from the following formula : 1 wl R = 7 7 . , in which 2 oh 2 R = modulus of rupture, w = pressure necessary to break the brick, / = distance between supports; b = breadth of brick, h = thickness of the brick. Cavities, pebbles and clay lumps seem to affect the transverse strength more than the crushing strength. There is often great lack of uniformity of different individual specimens tested. This may be due to irregularity in burning, a fact often overlooked by engineers and architects. The transverse test indicates the character of the brick's structure. It is claimed that the finer grained, more uniform and dense the structure of the brick, the higher its transverse strength; the better burned, the higher the transverse strength. As mentioned above, there is no definite relationship between modulus of rupture and crushing strength, and this fact is also brought out in the tables. 296 BUILDING STONES AND CLAY-PRODUCTS Absorption Test. An absorption test is made for the purpose of determining how much water a brick will absorb when soaked in water, it being supposed by many engineers, architects and others that the percer tage of absorption stands in direct relation to the frost resistance of the brick. This is not so. In the first place there are several ways of making the test, which yield somewhat different results. It may be made, (i) by complete immersion, usually for forty-eight hours, but sometimes even longer. (2) By partial immersion, and this for but a few hours, or longer, there being no standard rule. (3) By complete immersion in a vacuum. In discussing these it should be remembered that in making such a test we are endeavoring to imitate at least approximately the conditions to which the brick will be actually exposed when in use, and that we are not doing so will be apparent to anyone on a moment's reflection. When placed in a wall, a brick, unless set in damp ground or water, absorbs moisture only from one side, the side exposed to the weather and on which the rain spatters. So it probably soaks up much less than it does when tested in the laboratory. In whatever way the absorption test is made, the brick is first thoroughly dried and weighed. After soaking, the excess of moisture is wiped off the surface and it is weighed again, the per- centage of absorption being calculated in terms of the original dry weight. The results obtained by the several methods of testing are well brought out in a series of tests made on nearly ninety dif- ferent lots of Wisconsin brick. 1 Three pairs of half brick of each kind were used. One pair was completely immersed for 48 hours. A second pair was half immersed and its absorption measured at the end of 4 hours and again after an additional 44 hours' soaking. A third pair was completely immersed in water under a vacuum, so that the brick probably became completely saturated or nearly so. In the first of these tests, viz., complete immersion of 48 hours' duration, the percentage of absorption ranged from 5.8 per cent to 34.30 per cent. 1 Wis. Geol. and Nat. Hist. Surv., Bull. XVI, 1905. BUILDING BRICKS 297 In the partial immersion test it was found that in nearly every case the brick at the end of four hours had absorbed over 90 per cent of the total quantity they were capable of absorbing- after 48 hours' partial immersion. The method of manufacture and degree of density did not appear to affect the result in any way whatever. When immersed in water under a vacuum, the percentage of absorption ranged from 15.70 per cent to 39.90 per cent, and, as might be expected, the amount of water absorbed was greatly increased, so that the per cent gain for any one set ranged from 2.3 per cent to 69.6 per cent. No direct relation existed between the absorption and crush- ing strength. In making an absorption test it is better to make it on a half brick. The absorption will be less the harder the brick is burned, but this is less noticeable in very sandy clays. Repressed brick may show a lower absorption than unrepressed ones made from the same mixture and burned under the same conditions. Color is not necessarily a guide to the absorption power, except possibly when comparing bricks from the same kiln, in which case the darker ones, being commonly harder burned, may show less absorption. Absorption and porosity are not the same. Porosity refers to the amount of pore space in the brick. Absorption is ex- pressed in percentage terms of the dry weight of the brick; porosity is expressed in terms of its volume. The porosity may be determined by the following simple formula suggested by Purdy: i(w D}\ Percentage porosity = ioo()- -)> \(W S) I in which W = saturated weight, D = dry weight, S = weight of brick suspended in water. ' The saturation may be obtained by soaking the brick in water in a vacuum or by soaking for an hour in boiling water, the latter method being probably just as accurate. 298 BUILDING STONES AND CLAY-PRODUCTS A series of tests made by J. C. Jones, 1 indicated that the per- centage of absorption does not bear any constant ratio to the per cent of porosity. The porosity of clay products is, however, an important factor, probably, in their durability, and certainly in their cleanliness and non-conductivity of heat. If a brick is very porous the dirt will lodge in its pores and spoil its appearance, and this ap- plies more strongly to some other types of clay wares, as terra cotta. While no direct ratio exists between absorption and porosity, still we can say that a brick of high porosity will usually show high absorption and vice versa. A few figures from Mr. Jones' tests will illustrate: Per cent absorption, 2 weeks' soaking. Per cent porosity. Ratio per cent ab- sorption to per cent porosity. I 505 1.72 = 3-42 2 .576 2.04 = 3-54 23, 993 4.25 14.28 3 i. 08 2-97 :2.75 4 1.40 4.56 13.26 5 1-83 6.26 3-42 6 2-94 7.58 :2-57 7 4.28 10.90 :2.54 8 6.49 17.0 12.61 9 9.66 21 .60 : 2 . 23 10 ii .00 23-6 :2.i4 ii 11.80 25.8 :a.i8 12 15.10 29. 10 11.92 Some rather extensive tests on absorption and porosity of building brick by different methods have been made by Douty and Beebe. 2 The results of their tests are given in the following table. 1 Trans. Amer. Ceramic Society, IX. 2 " Some Further Experiments upon the Absorption, Porosity and Specific Gravity of Building Brick," Proceedings American Society for Testing Materials, Vol. XI, p. 767; see also " The Influence of the Absorptive Capacity of Bricks upon the Adhesion of Mortar," Proceedings American Society for Testing Materials, Vol. VIII, p. 518, 1908; also, Howard, Engineering News, Vol. 6, No. 10, p. 273, March, 1909. BUILDING BRICKS 299 COMPARISON OF RESULTS FROM FIVE METHODS OF DETER- MINING ABSORPTION WITH WHOLE AND HALF SPECIMENS, PREVIOUSLY DRIED TO CONSTANT WEIGHT AT 100 C. Partial immersion 90 days . Total immersion 90 days. Immersion 7 days and boil- ing I hour. Brick No. Whole. Half. Whole. Half. Whole. Half. Wt. Vol. Wt. Vol. Wt. Vol. Wt. Vol. Wt. Vol. Wt. Vol. 3 13-4 25-3 16.7 31-6 13-8 26.1 13-9 26.3 14.6 27-6 15-3 28.9 13 12. I 24.4 12.5 25-3 ii. 5 23.2 io-5 21 . 2 II . I 22.4 io-S 21.2 22 10.7 21.7 10.4 21 . I 10.8 2!. 9 n-3 22.9 II .2 22.7 IO. 2 20.7 2O 10.6 21.6 ii .0 22.4 10. 2 20.8 ii .0 22.4 n-5 2 3-5 n-3 23.1 21 9.2 18.4 10.7 21.4 10.3 20. 6 10.3 20. 6 II .0 22.0 10.4 20.8 8 8.4 17.6 8.9 I8. 7 10. I 21.2 9-3 19-5 8.9 I8. 7 8-9 18.7 18 8.0 16.3 8.0 I6. 3 7-9 16.1 8.1 16.5 8.4 I7.I 8-3 16.9 16 3-8 8-4 4-3 9-5 5-i ii. 3 4-9 10.9 3-8 8.4 5-o II .0 15 4.2 9-7 3-5 8.1 3-6 8-3 3-5 8.1 6-3 2-7 4-7 10.9 Aver- age . 18.2 10.4 18.8 18.7 18.3 19. 1 "'fe^ *y *? *-' O Boiling. Vacuum. Total immersion no days and boiling 4 hours. Brick No. Whole. Half. Whole. Half. Whole. Half. Wt. Vol. Wt. Vol. Wt. Vol. Wt. Vol. Wt. Vol. Wt. Vol. 3 14.0 26.5 13.2 25.0 I3-I 24.8 13-4 25-3 14.4 27.2 14-3 27.0 13 12.8 25-9 12.8 25-9 9-7 19.6 II .O 22. 2 ii. 9 24.1 II . I 22.5 2 n-7 23-8 II .2 22.7 9.8 19.9 io-5 21-3 ii. 6 23.6 ii. 8 24.0 2O ii . i 22.6 II .2 22.8 10.7 21.8 10.6 21 .6 10.7 21.8 n-3 23.0 21 ii .0 22. O 10.2 2O.4 io-5 21 .O 10.8 21.6 II . 2 22.4 10.9 21.8 8 10. 21 .0 10.7 22.5 9-2 19-3 8.0 16.8 10.8 22.7 9.9 20.8 18 8.5 17-3 8.6 17-5 7-2 14-7 7-2 14-7 8.7 17.7 8-7 17.7 16 6.0 13-3 5-6 I2. 4 3-o 6-7 3-3 7-3 6.0 13.3 5-7 12.7 IS 4-i 9-5 4-2 9-7 4.8 ii . i 3-5 8.1 4-9 H-4 4-4 IO. 2 Aver- age.. 2O. 2 19.9 17.7 17.8 20.5 2O. The methods of making these determinations are explained by them as follows: " Absorption by weight was obtained from the increase in weight of the specimens used in the determination of the spe- cific gravity of normal brick, maximum absorption. " Absorption by volume was obtained from the product of the absorption by weight and the specific gravity of normal brick. 300 BUILDING STONES AND CLAY-PRODUCTS It may be observed that these values approach very nearly the values for percentage of voids. That bricks 2 and 16 show higher absorption by volume than percentage of voids may be ascribed to the fact that specimens from bricks with a normal specific gravity higher than the average were probably selected. " Table III is a comparison of the results obtained by five methods of determining absorption with both whole and half specimens which were previously dried to a constant weight at o /~> ioo C. 11 In ' Partial Immersion ' the specimens were immersed to a depth of | inch. "In ' Total Immersion ' the specimens were submerged to a depth of \ inch. " In ' Total Immersion and Boiling/ the specimens were sub- merged for 7 days and then boiled for i hour. All partial im- mersion tests were conducted under as uniform conditions of air humidity and temperature as possible, i.e., ioo per cent humidity and about 68 F. " In ' Boiling ' the specimens were boiled 4 hours and weighed as soon as cool enough to handle and also 24 hours afterwards. In some cases there was a slight decrease after 24 hours and in others an increase. "In the ' Vacuum Test/ the specimens were subjected to a reduced pressure of about 68 cm. of mercury for i hour and, without breaking the vacuum, water was allowed to flow until the specimens were completely covered and then subjected to a pressure of about 35 Ibs. for i hour. " As the table given above is primarily a comparison of methods, the averages of absorption may be assumed to indicate the relative values of these different methods." Rate of Absorption. The same authors also endeavored to determine the rate of absorption for partial and total immersion of whole and half bricks by weight over an extended period of time. "At the expiration of no days the bricks were boiled four hours and the percentage of absorption obtained in this way was taken as the maximum or ioo per cent. The percentage rate at various periods was computed from this maximum. BUILDING BRICKS 3 OI " For both whole and half bricks, it was observed that ap- proximate maximum absorption is attained at an earlier period and the rate of absorption is higher in the case of total immer- sion than partial immersion, except in a few cases which can be accounted for by a variation in the specimens themselves. "Tests were made on several of the bricks to determine the effects of repeated absorption and drying. After repeating ab- sorption and drying ten times no appreciable change in the percentage of absorption or loss in weight could be observed." Permeability. Tests on the permeability of brick have been made by Douty and Beebe l for the purpose of determining whether any relation exists between the size or percentage of voids and the absorptive capacity. The tests were made on half brick mounted on Amsler-Laffon permeability apparatus and were subjected to a pressure of about 285 pounds per square inch. The results of these tests are given in the following table. RESULTS OF PERMEABILITY TESTS. Brick No. Specific grav- ity of normal brick, dried. Specific grav- ity of ground material. Voids, per cent. Permeability, cu. cm. per sq. cm. per min. Absorption by volume.percent. 3 1.89 2.66 28.9 I .600 26.5 13 2.02 2.64 23-5 0.500 21-5 2 2.03 2.6o 21 .9 1-957 22.7 20 2.04 2.65 22.9 2 .OOO 22.8 21 2 .00 2.60 23.1 3-230 21.2 8 2. 10 2.64 20.5 0.844 18.4 18 2.04 2-51 17.7 0.570 17.2 16 2 . 22 2.64 IO.9 0.282 12.4 15 2.32 2.64 12.1 0-594 6.8 1 As stated in their paper the data are considered incomplete because they were confined to a limited number of specimens and a comparison of the last three columns of the preceding table would seem to indicate that the largest values of permea- bility are obtained for those brick in which the absorption by volume nearly approaches the percentage of voids. 1 " Some Further Experiments upon the Absorption, Porosity and Specific Grav- ity of a Building Brick," Proceedings American Society for Testing Materials, Vol. XI, p. 767. 302 BUILDING STONES AND CLAY-PRODUCTS Relation between Crushing Strength, Transverse Strength and Absorption. There seems to exist a strong misconception on this point. The compressive strength cannot be correlated with the absorption, except when such comparison is restricted to samples of the same clay, molded and burned under uniform conditions. There is, as already mentioned, no definite relation between the transverse and crushing strength, and this fact is also brought out in the tables. A brick of low transverse strength may be of good crushing strength and vice versa. The lack of definite relation between the crushing strength, transverse strength and absorption is shown by the following figures taken from a series of tests made on a number of Wis- consin brick. Kind of brick. Average crush- ing strength. Average modu- lus of rupture. Per cent ab- sorption. Soft mud IIO2 526 2O ?,Z Soft mud AC72 s6o 14- 4- Soft mud 3036 1063 18 7 Soft mud C7o6 1062 22 2< Stiff mud Stiff mud 1540 2708 588 crco 34.3 27 .6 Stiff mud 2234 IOQ7 24. 15 Stiff mud 4006 IOQO 20 8q Stiff mud I^4O 588 2A 2 Stiff mud ^IIO 2IQO Soft mud Soft mud 1192 4-^72 526 e6o 24.65 14 4 Fire Tests. Freitag 1 states that " many fires have fully demonstrated the fire-resisting qualities of good brickwork. Its ability to withstand fire and water tests depends on: (a) the method of manufacture, (b) the chemical properties of the ma- terials employed, (c) the method of use. " Both the Baltimore and San Francisco fires demonstrated that good quality brickwork, used for walls or column casings, suffered less than any other material. 1 " Fire Prevention and Fire Protection," p. 219. BUILDING BRICKS 303 " Ordinary well-burned brick of good quality is the most satisfactory fire-resisting material now used in building con- struction. When the walls were laid with hard brick, with plenty of headers and in portland cement mortar, and were properly tied to the floor and roof members, there was little if any damage." A fire test of brick is of great importance. When such a test is made, it is customary to heat a sample of the brick to redness in a furnace and then plunge it into cold water. This may be satisfactory if no other means is at hand. A far better, though expensive, plan is that formerly followed in the fire-testing station of Columbia University, under the direction of Professor I. A. Woolson. A house was constructed with exterior dimensions of 14 feet 6 inches by 9 feet 6 inches, consisting of reinforced concrete walls and roof, while the side walls were removable. The floor of the building is a grate upon which the fire is built and suitable draft openings and chimneys are provided. The sides were built as 8-inch walls of the brick to be tested. The brick were laid in bands about 14 inches wide, in order that each variety of brick might be subjected to the same heat, and as far as possible only half a band was laid on the same level in the wall; the other half was placed in some other position. The purpose of the test is to determine the effect of a continuous fire against the walls for two hours, bringing the heat up slowly to 1700 F. during the first half hour and maintaining this as nearly as possible during the remainder of the test. Then a one and one-eighth-inch stream of cold water was thrown against the wall for three minutes at hydrant pressure, which varied from 25 to 30 pounds. In one test several large cracks developed in the walls and the brick themselves were full of cracks. Indeed, it was very difficult to get a whole brick. In general, the brick were affected by the fire about half way through. Samples of the brick tested for their crushing strength after the fire test showed in nearly every case a marked decrease. 304 BUILDING STONES AND CLAY-PRODUCTS A testing furnace 1 in use at the Underwriters' Laboratory of Chicago consists of a gas furnace with " a movable steel frame fire-brick wall or door 14 inches thick that shuts off the furnace from a radiation chamber." . . . "This movable wall has an arched opening 6 feet wide and 9 feet high. The material to be tested is built up in this opening as a panel." After the panel is filled and shoved into place, the fire chamber is heated by gas. An effort was made to obtain the maximum temperature, 1700 F., within one-half hour after starting the test, and to maintain this temperature as nearly constant as possible for two hours. At the end of this time the panel con- taining test brick was pulled out and a stream of water from a 1-inch nozzle at 50 pounds pressure directed against the hot surface for a period of five minutes. These conditions were unusually severe, and the temperatures were those not usually reached in an actual fire. Much of the damage done was due to internal stresses, be- cause gas flame of the furnace heated one face more rapidly than the other face. Many of the materials were poor non-conductors of heat, the natural building stones and tiles proving specially bad in this respect. This naturally set up stresses which the webs of ordinary hollow blocks were insufficient to resist. Brick panels withstood tests better than other materials and comprised unused new Chicago brick and used St. Louis brick. Fifty per cent of the new brick were split, while 60 to 70 per cent of the old brick were not damaged. Lime knots apparently caused damage. The bricks at back of panels were unaffected. Hydraulic pressed brick stood the test very well and 70 per cent were found sound after quenching. The tile tested behaved badly. One was a hollow-glazed building tile, 8 by 8 by 16 inches, with ^-inch web and four core holes running throughout its length. The other, a partition tile, 5 by 12 by 12 inches, with a f-inch web, .and three core holes. 1 U. S. Geol. Survey, Bull. 370. BUILDING BRICKS 305 Unfortunately, no detailed and conclusive series of tests have been made to determine the relative fire resistance of brick made by different methods. Vitrified bricks will usually spall badly when subjected to fire and water treatment. Stiff-mud brick, if at all laminated, show a tendency to split off along the planes of lamination. And yet, brick will on the whole stand fire better than most building stones. Coefficient of Expansion. The following tests of coefficients of expansion of burned clay wares is of interest in this connection. These tests were made at the Watertown Arsenal, 1 the brick being heated in a hot- water bath. COEFFICIENTS OF EXPANSION OF BRICKS, AS DETERMINED IN WATER BATHS. Character of product. Original gauged length in air. Hot. Cold. Differ- ence. Difference in length. Coefficient of expansion. Red brick, No. i Red brick, No. 2 Red brick, No. 3 Red brick, No. 4 Fire brick, No. i Fire brick, No. 2 Hollow fireproof building brick 6.0852 6.OIOQ 5-9396 6.0204 5.9968 5.9988 10 0036 X 00 00 00 00 00 OO 34 34 34 34 34 34 T.A O O O O O O H IO IO IO f> IO vr> H .0032 .0023 .0023 .0029 .0026 .0022 OO44 .00000351 .00000255 .00000258 .00000321 .00000289 .00000244 00000291 Frost Test. There is no universally accepted standard method of making this test. Some engineers take either a whole or half brick, soak it thoroughly in water from two to even five days, and then put it in a refrigerating chamber where it is exposed to a freezing tem- perature for perhaps 23 hours, followed by one hour thawing at a temperature of about i2oF. This process is repeated pref- erably about twenty times and the loss in weight or evidence of disintegration noted. The work of the Iowa Geological Survey on bricks from that state 2 has shown that rough Cubes when subjected to the freezing 1 Tests of Metals, etc., 1890. 2 Iowa Geological Survey, XIV. 306 BUILDING STONES AND CLAY-PRODUCTS test gave greater losses than smoother and larger ones respec- tively. Their conclusions were based on 20 hours' freezing and 4 hours' thawing, repeated thirty times. It has been noticed 1 that the method of placing bricks in a freezing box may also cause difference in the results. Thus, if the brick are placed close together, the evaporation that takes place from the surface of a warm brick when placed in the refrigerating chamber is retarded. More water remains in the pores, and the brick will be more damaged. If the same brick are separated when placed in the freezing box, a lower percentage of loss or disintegration occurs. This fact was dis- covered by the different reports made by two laboratories, in testing brick of the same make. The one in which the brick were frozen in a closely set position reported a far greater loss. There is some doubt as to what are the causes governing the frost resistance of brick, but the common idea is that the harder burned a brick the greater its frost resistance. This theory is based on the fact that with increased hardness of burning, there is an increase in strength and decrease in pore space. It is claimed by some, however, that freezing tests on brick do not bear this out; moreover, the crushing strength of some of the hardest brick is most affected by freezing. Of course, the degree to which a given brick is affected will depend to a certain extent upon its degree of saturation. If the pores are not completely filled with water there may be room for the latter to expand in freezing without exerting any internal pressure, while if the pores are filled, then, unless the water can force its way out in freezing, considerable internal pressure may develop. Jones 2 suggests that the power of a brick to withstand frost action depends on the amount of pore space, the rate at which water can flow through the pores, and the crushing strength. A very porous brick may drain more easily, provided the pores are large and straight, so that some of the water may drain off before freezing. If the pores are tortuous, the water may not 1 Tonindustrie Zeitung, XXXII, p. 1846, 1908. 2 Trans. Amer. Ceramic Society, IX, p. 528, 1907. BUILDING BRICKS 307 only drain off more slowly, but, if it freezes, remain within the brick. The crushing strength may indicate the relative resistance which a brick will offer to the expansive force of freezing water. Hard-burned brick have greater strength and greater rigidity than soft-burned ones, and while they have a smaller pore space, and have less water when filled, still they drain more slowly, and, though having greater strength to resist expansion, will rupture with less expansion. A given amount of expansion on freezing might, therefore, rupture a rigid brick, when it would not harm a more elastic or a tougher one. If brick are to be used in the foundation where they are liable to be exposed to moisture it is best to use those of high crushing strength and low porosity. Proposed Standard Specifications for Building Brick. The following have been proposed by the American Society for Testing Materials. 1 Selection of Samples. For the purpose of tests, brick shall be selected by some disinterested and experienced person to represent the commercial product. All brick shall be carefully examined, and their condition noted before being subjected to any test. Transverse Test. At least five brick shall be tested, laid flat- wise with a span of 7 inches, and with the load applied at mid- span. The knife edges shall be slightly curved in the direction of their length. Steel bearing plates, about J inch thick and ij inches wide, may be placed between the knife edges and the brick. The use of a wooden base-block, slightly rounded trans- versely across its top, upon which to rest the lower knife edges, is recommended. The modulus of rupture shall be obtained by the following formula: in which e is the distance between supports in inches, b is the breadth and d the depth of the brick in inches, and W is the load in pounds at which the brick failed. 1 Vol. IX, p. 131. 308 BUILDING STONES AND CLAY-PRODUCTS The half bricks resulting from the transverse test shall be used for the compression and absorption tests. One half shall be crushed in its dry condition; the other half shall be used for the absorption test and crushed while in its wet condition. No specimen shall be used if any part of the line of fracture is more than i inch from the center line. Compression Test. Compression tests shall be made on half brick resulting from the transverse test. The brick shall be bedded flatwise on blotting paper, heavy fibrous building paper or heavy felt, to secure a uniform bearing in the testing machine. In case the brick have uneven bearing surfaces, they shall be bedded in a thin coat of plaster of Paris. For the dry test, before applying the plaster of Paris, the bearing surfaces of the brick shall receive a coat of shellac. The machine used for compres- sion tests shall be equipped with spherical bearing blocks. The breaking load shall be divided by the area in compression, and the results reported in pounds per square inch. Absorption Test. At least five half brick shall be first thor- oughly dried to constant weight, at a temperature of from 200 to 250 F., weighed, and then placed on their face in water to a depth of i inch in a covered container. The brick shall be weighed at the following intervals : one-half hour, six hours, and forty-eight hours. Superfluous moisture shall be removed before each weighing. The absorption shall be expressed in terms of the dry weight, and the balance used must be accurate to 5 grams. Freezing and Thawing Tests. In case the freezing and thawing test is desired, at least five brick shall be thoroughly saturated by immersion in cold water, which shall be raised to 200 F. in thirty minutes, and then allowed to cool. The specimen shall be immersed in ice water for not less than one hour, weighed, then transferred to the refrigerator and supported in such a manner that all faces will be exposed. The specimen shall be subjected to a temperature of less than 15 F. for at least five hours, then removed and placed in water at a temperature of not less than 150 F., nor more than 200 F., for one hour. This operation shall be repeated twenty times, after which the brick, still saturated, shall be weighed again. The character of the BUILDING BRICKS 39 brick shall be noted before and during the test, and all visible changes recorded. Immediately on completion of this test, the samples are to be thoroughly dried and subjected to the trans- verse and compression tests. Requirements. The following requirements shall be met. The modulus of rupture shall be as follows: Average, Ibs. Minimum. For samples thoroughly dry AOO 22*; For samples thoroughly saturated For samples subjected to freezing and thawing process 275 27^ 22 5 22Z The ultimate compression strength shall be as follows: Average, Ibs. per sq. in. Minimum, Ibs. per sq. in. For samples thoroughly dry 3000 2SOO For samples thoroughly saturated 2 Tf t^. M Qs 3 rj- ON rj- t^MOO H v CO H 00 "3- Tf t^MOO ^ o CS VOO4CO Alhambra 17.) 18. Glazed white . . 19. Glazed ivory A series of tests made to determine the wearing qualities of flooring materials was published in the Scientific American for July 3, 1897. They are of interest as showing the comparative wearing qualities of floor tile and other materials used for the same purpose. The following statements are quoted from this article. The materials tested were rubber tile, English earthen- ware tile, Vermont marble, marble mosaic, flagstone, Oregon pine, teak wood, white pine and oak. The experiments were carried out by Messrs. William Gray & Sons, and were made under the careful supervision of Mr. William J. Gray. In carrying out the tests the specimens were cemented to iden- tical blocks of sandstone, each of which weighed twenty-one pounds. The samples represented a surface six inches square, and the thickness of each sample was the same as that commonly used in the various floorings. The interlocking rubber tile speci- men was f inch thick, the No. i Vermont marble was i inch thick, the Oregon pine 2\ inches thick, and so on. The samples were all placed face downward upon a horizontal iron rubbing wheel 10 feet in diameter, which was run for a period of one hour at a speed of 75 revolutions per minute. A suitable frame held the blocks loosely in place and prevented WALL AND FLOOR TILE 371 them from rotating with the wheel, care being taken to let the full weight of the blocks bear upon the wheel. The face of the wheel was freely supplied during the test with the best sharp rubbing sand and water. The results were full of surprises. By far the best showing was that made by the interlocking rubber tile, which only lost g*$ inch as the result of an hour's grinding. On the other hand, the marble mosaic collapsed altogether, the one-inch strip being rubbed entirely away within fifteen minutes under a pressure of a little over half a pound to the square inch. The whole slab disappeared in thirty-five minutes under the same pressure. Next to the rubber, the English earthen tile showed by far the best results, losing only f inch in thickness; and of the stones, the granolithic made the best showing, losing f inch, flagstone coming next with y 9 g inch wear. The marbles wore away very fast, No. i Vermont marble losing f of an inch. Their average resistance, indeed, was not as high as that of the woods. One of the most curious results is shown in the action of the woods, where teak lost nearly double as much as the softer white pine, the wear being respectively ^f and -$ of an inch. Yellow pine showed the same wear as white pine, and the oak specimen lost the same amount as its great rival Oregon pine, which was reduced by f inch. CHAPTER XIV. SEWER PIPE. Raw Materials. This class of ware, which is sometimes called sanitary pipe, is made from a clay or shale, or mixture of two or more kinds of these materials, whose physical properties are such that they will either burn to a vitrified body or one of low absorption and also take a salt glaze. In some sewer-pipe mix- tures a fire clay is used as one of the ingredients, in others only non-refractory clays are employed. Manufacture. Sewer-pipe clays are thoroughly ground if necessary, well mixed and then molded in a special form of press, from which the clay issues through a die of the proper form. Special shapes, such as traps, sockets and elbows, are usually made by hand in plaster molds and require careful drying. At times Y shapes are made by cutting one straight piece on the slant and joining it onto a pipe with wet clay. T's are made in a similar manner. Sewer-pipe are slowly dried on slatted floors, heated by steam pipes, and burned in down-draft kilns. When the kiln has reached a temperature of not less than 1150 C., salt is thrown into the fires and the sodium vapors passing through the kiln, unite with the clay, forming a glaze on the surface of the ware known as a " salt glaze." Many clays are capable of taking a good salt glaze, but some take a poor one, and others do not glaze at all. A poor salt glaze might be due to the character of the raw material, too low temperature of burning, or the latter combined with presence of an excess of soluble salts. A sewer pipe is sometimes glazed with an easily fusible clay, known as a " slip clay." This is applied to the surface of the pipe previous to burning and melts to a glassy coat at the tem- perature of firing. This practice has been abandoned in the 372 SEWER PIPE 373 United States, as the salt glaze is cheaper and equally satis- factory. Sewer pipes are made in diameters from 3 up to 36 inches. The following table of data, taken from the catalogue of one large manufacturer, may be of interest: Inside diameter, inches Weight per foot in pounds Area in inches No. of feet in average car load . . Thickness in inches . . 3 7-5 7 3400 4 IO 12 2600 2000 16.5 28 1599 IOOO QOO 28 64 12 39 113 15 58 177 750 600 400 300 It 21 105 254 345 240 if 125 190 140 390 455 1 80 if The following data of a somewhat different character are taken from the catalogue of another company: APPROXIMATE WEIGHTS, DIMENSIONS, ETC., STANDARD SEWER PIPE. Calibre, inches. Thickness, inches. Weight per foot, pounds. Depth of sockets, inches. Annular space, inches. 2 A 5 li 1 3 i 7 l i 4 i 9 if f 5 f 12 if f 6 f 15 if f 8 f 23 2 f 9 if 28 2 f IO f 35 2* f 12 43 2* 1 15 1 60 2? i 18 i 4 85 2f i 20 | IOO 3 i 21 I 120 3 1 22 f 130 3 I 24 f 140 3i i 27 2 224 4 f 30 2| 252 4 f 33 2j 310 5 it 36 2* 35 5 "* 374 BUILDING STONES AND CLAY-PRODUCTS DOUBLE STRENGTH PIPE. 15 tl 75 ,, \ 18 if 118 2\ 1 20 if 138 3 | 21 if 148 3 1 22 if 157 3 i 24 2 190 3* | 27 2i 265 4 1 30 2i 290 4 1 33 2| 335 5 i| 36 2| 375 5 i.i Requisite Qualities. Sewer pipe should be free from pimples, blisters and cracks; the glaze should be continuous and as smooth as possible; the pipe should be straight and free from cracks. A dark color is preferred by most engineers arid architects. The cause of the defects are the following: Blisters may be due to air imprisoned in the clay during mold- ing. Surface pimpling, found more or less on salt glazed pipe, appears to be related to the texture of the body and treatment during firing. To state it in more detail: The pimples are caused by incipient fusion, bubbling and swelling of small par- ticles of shale, or perhaps concretionary matter (such as pyrite and limonite) lying close to the surface. They can be prevented usually by finer grinding of the raw material. Rapid burning seems to encourage their development. Poor glaze may be due to the clay, too low heat in firing or not enough salt. Warping and cracking may be due to uneven mixing, uneven heating or inability of pipes to stand weight of those set on top of them in the kiln. Fine cracks may develop in the drying and open still further in the burning. In preparing a set of specifications for sewer-pipe tests, the committee of the American Society for Testing Materials has pointed out the existence of the following demands. 1 .(a) Strength. This includes resistance against rupture, homo- geneity of the material and the vitrification of clay pipe. 1 Vol. IX, p. 263. Channel Pipe .Socket Pipe Running Trap P Trap PLATE LIX. Sewer pipe and fittings. 375 SEWER PIPE 377 It includes also the necessary data for the thickness of shell and the importance of fire cracks in vitrified pipes. The proper requirements should be stated for the strength necessary to resist crushing, bursting and impact under various practical conditions. (b) Durability. This includes resistance to wear and tear. There should be given the required resistance against abrasion by sand or gravel at high velocities in glazed and unglazed pipes, the density or specific gravity of the material with relation to its porosity and capillary absorption of moisture. There should be considered the corrosion of glazed and un- glazed vitrified clay pipes by acids, alkalies, steam, frost and gases. (c) Serviceability. This relates to the efficiency of the pipes to perform the best service. Under this heading should be considered the question of smoothness, the glazing of vitrified pipes, blisters, the best sectional form for various purposes, and the warping of pipes, including the permissible deviation from true, straight pipes and regular curves or specials. The best lengths of the individual straight pipes and specials should be determined. The ends of pipes with reference to making the best joints should receive most careful study to determine the best practice for different conditions, including hub and spigot, butt and collar, and beveled joints. All specials, such as branches, spurs, curves, etc., should re- ceive attention with reference to recommendations as to size and form. Specifications. The following specifications for sewer pipe are given by Johnson in his work on Engineering Contracts and Specifications. Straight sections are termed "pipes"; branches, bends, re- ducers, etc., are fittings, " specials " or special pieces. All hubs or sockets should be of sufficient diameter to receive spigot end of next following pipe or special to full depth, without chipping, and leave J inch all around for mortar. 378 BUILDING STONES AND CLAY-PRODUCTS In the case of pipes and specials 12 inches and upward in diameter at least 40 per cent shall be truly or substantially cir- cular. If less than 12 inches in diameter, at least 60 per cent circular. Of those that are not circular all that show long diameter more than from 6 to 7 per cent greater than short one are to be rejected. Pipes and specials showing angles, sharp curves or flat curves to be rejected. A single fire crack extending through whole thickness of pipe must not be more than two inches long at spigot end or more than one inch long at hub end, measured from shoulder in the latter case. Two or more such cracks at either end cause rejection. A single fire crack extending through two-thirds of the thick- ness of pipe must not be over four inches long. Two or more such cracks cause rejection. A single fire crack extending through one-half of the thick- ness must not be over 6 inches long. Two or more cause rejection of the pipe. A single fire crack extending through less than one-half of the thickness of the pipe must not be over 8 inches long. Two or more cause rejection. A transverse fire crack must not be longer than one-sixth of the circumference or more than one-third of the thickness in depth. Two or more cause rejection. No fire cracks shall be over one-eighth of an inch wide at widest point. No combinations of above limitations allowed except by special consent. Any pipe or special cracked through whole thickness from any other cause than burning rejected. This refers to transporta- tion, cooling, frost, etc. Irregular lumps or unbroken blisters on interior surface suffi- cient to appreciably retard flow cause rejection. Broken blisters or flakes must not exceed in thickness one- sixth of the thickness of the pipe or in greatest diameter one-twelfth of the circumference of the pipe. Any broken blister or flake so placed that proper fitting of pipe cannot bring it on top will cause rejection. SEWER PIPE 379 The same applies to broken blisters on outside. Any pipe showing in any manner a want of thorough vitri- fication or fusion or use of improper materials or methods shall cause rejection. All pipe supposed to be straight shall not show any material deviation. No piece broken out of rim of either hub or socket of pipe shall be greater than one-tenth of the circumference of the pipe. And any break, even within limits, shall cause rejection if pipe cannot be fitted so as to bring break at top. A. Mars ton 1 points out that the standard tests of drain tile and sewer pipe should develop two cardinal qualities: (a) The bearing strength of the pipe under approximate conditions and for which he proposes a direct bearing-strength test, (b) The quality of the material in the shell of the pipe to resist disinte- gration, which he proposes to determine by: 1. The modulus of rupture of the material, calculated from the data of the bearing-strength test, to show the strength of the material. 2. An absorption test of the material to show its resistance and the penetration and action of destructive agencies. The need of standard tests is shown by the fact that in many cases large pipe are found to be cracked when inspected in building sewers and drains, and that this cracking is sometimes caused by comparatively shallow depths of ditch filling. As a result of numerous experiments in Iowa, the Iowa En- gineering Experiment Station has devised the following speci- fications for standard tests: Iowa Standard Specifications for Drain Tile and Sewer Pipe. Absorption Tests, i. Specimens. The specimens shall be each approximately three inches square, and shall extend the full thickness of the pipe wall, with the outer skins unbroken. 2. Number of Test Specimens. Five individual tests shall constitute a standard test, the average of the five and the result for each specimen being given in the report of the test. 1 Proceedings American Society for Testing Materials, Vol. XI, p. 833; see also " Municipal Engineering," Vol. 30, p. 288, and Vol. 34, p. 294. 380 BUILDING STONES AND CLAY-PRODUCTS 3. Drying Specimens. Each specimen shall be dried in an oven, or by other application of artificial heat, until it ceases to lose further appreciable amounts of moisture when repeatedly weighed. 4. Brushing Specimens. All surfaces of the specimens shall be brushed with a stiff brush before weighing the first time. 5. Weighing. The specimens shall be weighed immediately before immersion, on a balance or scales capable of accurately indicating the weight to within one-tenth of one per cent. 6. Water for Standard Test. The water employed in the standard absorption test shall be pure soft water, at the air temperature of a room which is artificially heated in cold seasons of the year. 7. Immersion of Specimens. The specimens shall be com- pletely immersed in water for a period of 24 hours. 8. Re-weighing. Immediately upon being removed from the water, the specimens shall be dried by pressing against them a soft cloth or a piece of blotting paper. There shall be no rub- bing or brushing of the specimen. The re-weighing shall be done with a balance or scales capable of accurately indicating the weight to within one- tenth of one per cent. 9. Calculation of Result. The result of each absorption test shall be calculated by taking the difference between the initial dry weight and final weight, and dividing the remainder by the initial dry weight. Bearing Strength, i. Specimens. The specimens shall be unbroken, full-sized samples of the pipe to be tested. They shall be carefully selected so as to represent fairly the quality of the pipe. 2. Number of Specimens. Five individual tests shall con- stitute a standard test, the average of the five and the result for each specimen being given in the report of the test. 3. Drying. The specimens shall be dried by keeping them in a warm, dry room for a period of at least 2 days prior to the test. 4. Weighing. Each dried specimen shall be weighed on reli- able scales just prior to the test. 5. Bedding of Specimen for Test. Each specimen shall be accurately marked, with pencil or crayon lines, in quarters, prior to the test. Specimens shall be carefully bedded above and below in sand for the one-fourth circumference of the pipe, measured on the middle line of the tile wall. The depth of bedding above and below the tile at the thinnest point shall be SEWER PIPE 381 equal to one-fourth the diameter of the pipe, measured between the middle lines of the tile walls. 6. Top Bearing. The top-bearing frame shall not be allowed to come in contact with the tile or the test load. The upper surface of the sand in the top bearing shall be carefully struck level with a straight edge, and shall be carefully covered with a heavy rigid top bearing, with lower surface a true plane made of heavy timber or other rigid material capable of uniformly distributing the test load without any appreciable bending. The test load shall be applied at the exact center of this top bearing in such a way, either by the use of a spherical bearing or by the use of two rollers at right angles, as to leave the bear- ing free to move in both directions. In case the test is made without the use of a machine and by piling on weight, the weight may be piled directly on a platform resting on the top bearing, provided, however, that the weight does not touch the top frame holding the sand, and provided, further, that the weight is piled in such a way as to insure uniform distribution of the load over the top surface of the sand. 7. Frames for Top and Bottom Bearings. The frames for the top and bottom bearings shall be composed of timbers so heavy as to avoid any appreciable bending by the side pressure of the sand. The frames shall be dressed on their interior surfaces. No frame shall come in contact with the tile during the test. A strip of soft cloth may be attached to the inside of the upper frame on each side along the lower edge, to pre- vent the escape of sand between the frame and tile. 8. Sand in Bearings. The sand used for bedding the tile at the top and bottom shall be washed sand which has passed a No. 8 screen. It shall be dried by keeping it spread out thin in a warm, dry room. 9. Application of Load. The test load shall be applied grad- ually and without shock or disturbance of the tile. The appli- cation of the load shall be carried on continuously, and the tile shall not be allowed to stand any considerable length of time under a load ^smaller than the breaking load. 10. Calculation of the Bearin r Load. The total breaking load shall be taken as equal to tl total top load, including the weight of top frame, sand for top bearing, top bearing timbers, etc., plus five-eighths the weight of the pipe. This total load shall be divided by the length of the pipe in feet so as to give the bearing strength per linear foot of pipe. Computing the Modulus of Rupture. The modulus of rupture 3 82 BUILDING STONES AND CLAY-PRODUCTS for drain tile and sewer pipe shall be computed from the results of the standard test for bearing strength, according to the following rule: Divide the bearing strength per linear foot by twelve, mul- tiply the quotient by the radius of the middle line of tile wall expressed in inches, and divide this product by the square of the minimum thickness of the tile wall at top or bottom, also ex- pressed in inches. This quotient will be the modulus of rup- ture of the pipe, expressed in pounds per square inch. The formulas on which the above specifications are based are derived in the usual manner for flexible rings subjected to uniform vertical loads, over 90 of the circumference above and the same distance below. The mathematical details of the derivation will not be given. Use is made in work of both the static and the elastic equations of equilibriums. BRIEF SUMMARY OF ABSORPTION TESTS OF DRAIN TILE AND SEWER PIPE. IOWA STANDARD METHOD. Tests of Clay Drain Tile. No. of tests. No. of kinds. Diameter of tile, ins. Per cent of absorption. Minimum. Maximum. Average. 4 30 2 42 5 4 5 I 3 2 2 I I I 6 8 12 18 28 30 15-0 2 . 6-4 . 18-5 7-3-8-3 16.3 4.8-6.1 3.6-19.0 5-0-5-8 5-5 5-4 4-3 2-4-3-Q 4.1 4.8 3-4 7-6 8.8 6.1 5-2 Other Proposed Standard Tests. A number of other meth- ods of making bearing-strength tests of drain tile and sewer pipe have been advocated or used. Together with the above method, they may be enumerated as follows: 1. Completely surrounding the pipe with sand in a very strong box. The author understands that this method was in use for a time in Brooklyn. It has been strongly advocated by Blackmer and Post of St. Louis, in recent correspondence, and they have made a new design for the enclosing box and the bearings. 2. Bedding the pipe on sand at the bottom, while applying the top load to a narrow bearing strip. The author would designate this the Brooklyn Method, as it is in regular use by the sewerage engineers of that city. SEWER PIPE 383 O O O o co O OO ON O^ t-^. ! MMQMOMOOOQ 1 LOICNllCOONONO OOOOOcoOOOOOco O M O O O O VO 1 VOOO ONOO M O CO M O O 1 1 VO 1 OO 1 ^ ON ^ O) voOO ON w t^- M M CO CO i_, 1 VO C^ C*4 t^- O co M OO vo G fH M M M H 3 PQ Minimum. O O O - OO o vo ON O H O O O O CO 1 ON ON CO t^ ^ O OO VO vO M M t^ M M M CS vo M s C/2 | a 6^ I vovO t^^oO O ^ OO ^OO O VO 00 O Fig. 20. Sections of sewer blocks. (American Sewer Pipe Company.) The following data are taken from the catalogue of the Ameri- can Sewer Pipe Company. SEWER PIPE 387 JA M Foot of sewer. xoOOooQO^OO^MTi-'^- i^ u-> c> o O O Q O t~~ O^ O 1-1 -i Ho *-|oo Ho H>H H He Ho Ho Ho >HH H kj .S -* nf-41 mN - - t-|ao t- ^ i- -r t-|oo t-|oo t-|oo t-|oo ^ t>| H H HW ISP < .S H^ inloo ia|oe )oo 1 io|oo m|oe l io|oo |oo 1 !* 1 bi .9 rt|2 n|- !* !* ^12 n|-* HH 35 Sp S|S Sp t-|oo dimensic d .an.*** ^Sp^SS^ - M H H 1 h! H^ t-|oo t-loo t>|oo HH t-| H H H Ho Sp H O &5 o5 |ao inloo inloo nW ^H H|OO ""G ""P lao io|oo t-|oo _C vOvO t^-t^OO ONO^O 388 BUILDING STONES AND CLAY-PRODUCTS SANITARY WARE. Sanitary ware is divided into two classes, viz.: (1) Vitreous Ware, from which are made water-closets, tanks, high and low lavatories and drinking fountains. This class of ware is made in two fires, viz., biscuit and glost fire. (2) Solid Porcelain, so called in the trade, the body being made of fire clay and fire-clay grog, which is covered with a white vitreous lining, the latter in turn being covered with a hard, clear, feldspathic glaze. The lining and glaze are applied to the green ware, and the whole burned in one fire in a rec- tangular muffle kiln. In this type are made solid porcelain bath- tubs, urinals, stalls, laundry trays, kitchen and pantry sinks, slop sinks, lavatories, etc. It is sold as A, B, C grades. When the white lining is omitted a buff-colored ware results, which is of a cheaper grade and known as Continental ware. Raw Materials. The body of vitreous ware consists of several grades of kaolin, ball clay, whiting, flint and feldspar. The body of solid porcelain ware is made of a mixture of several grades of fire clay and fire-clay grog. The glaze of the former consists of feldspar, Cornwall stone, 1 whiting, zinc oxide, white lead, kaolin, flint and boric acid, while the glaze of the solid porcelain ware is similar but contains no lead and tin oxide. Manufacture. Sanitary ware is formed by hand in plaster molds. Great care has to be taken to mix the clays properly and to dry the ware slowly after it has been formed. Vitreous ware is first burned to the " biscuit " condition, then glazed and fired again in the glost kiln, but at a lower temperature, in order to fuse the glaze. The solid porcelain has the glaze applied to the green ware and the whole fired in one operation. Properties of Sanitary Ware. The body of both kinds of sanitary ware should be steel hard, and the vitreous ware is non-absorbent. They should not discolor, and the glaze should be smooth and free from cracks. The visible defects are chiefly in the glaze, which may dunt, fire crack, or craze. It may also shrink away from the edges of 1 A partially decayed granite. SANITARY WARE 389 the ware. The glaze may also show green or brown spots. If underfired it is dull, if overfired it blisters. Proper shrinkage of the ware in burning is highly important. The disadvantages claimed for marble, slate and soaps tone, as compared with clay ware, are that they lack uniformity of color, are not non-absorbent, and in the case of marble at least are affected by acid waters. Glass is claimed to be more brittle than the clay ware. Enameled iron ware is said by some to be less durable. Sanitary ware made of burned clay is now widely used in the United States. It has grown tremendously in favor in recent years and has also improved greatly in quality. Much was formerly imported from Europe. An objection urged by some is the higher cost and great weight. A finished bathtub may commonly weigh from 500 to 800 pounds, according to size and shape. GLOSSARY. Adobe. A sandy, often calcareous clay, much used in warm climates for making sunbaked (adobe) brick. Air shrinkage. The decrease in volume which a clay undergoes in drying. Air brick. A hollow or pierced brick built into a wall to allow the passage of the air. Alabaster. A white, massive variety of gypsum. Amphibole. A group name including a number of mineral species, which are essentially silicates of alumina, magnesia, lime and iron. They are found in both igneous and metamorphic rocks. Hornblende is the commonest species. Anticline. An arch-like fold. Apatite. A mineral occurring in many granites, but usually in small quantities. It is a phosphate of lime and has a hardness of 5. Aplite. A line-grained granite, consisting normally of quartz and feldspar, and usually occurring in dikes. Aragonite. A mineral having the same composition as calcite (calcium carbonate) but differing from it in crystalline form. Arch brick. Commonly applied to those brick taken from the arches of a kiln. They are usually overburned. Argillaceous. A common term applied to rocks containing clayey matter. Arkose. A variety of sandstone containing much feldspar. Ashlar brick. A term often applied to certain brick whose one edge is rough chiseled to resemble rock -faced stone. Ball clay. A plastic white-burning clay used as a bond in china ware. Basalt. An igneous rock of volcanic character, composed chiefly of pyroxene and plagioclase feldspar. It is usually fine-grained and black, is common in the northwestern states, but is little used for building purposes. See Trap. Bastard granite. Many quarrymen apply this term to gneissic granites. Bate. See False cleavage. Bedding. See Stratification. Biotite. A mica, essentially a silicate of aluminum, magnesia and iron, of black or dark green color. Black coring. The development of black or bluish black cores in bricks, due to improper burning. Blind seams. Incipient joints. Bluestone. An indefinite term commonly applied to sandstones of a bluish gray color. In Maryland it is used for a gray gneiss, and in the District of Columbia for a mica schist. The well-known bluestone of eastern New York is used for flagging. Book tiles. Flat, hollow shapes, having two segmental edges and resembling a book in section. Boulder quarry. A quarry in which the joints are numerous and irregular, so that the stone is naturally broken up into comparatively small blocks. 390 GLOSSARY 391 Breccia. A rock composed of angular fragments, usually cemented together. Brick clay. Any clay that can be used for brick manufacture. Brownstone. A term properly referring to a brown sandstone, but now very loosely used. Calcareous. Containing lime, as a calcareous sandstone or calcareous day. Calcareous tufa. A porous mass of lime carbonate, deposited around the mouth of springs, as in swamps, or on rock ledges. It often forms a coating on plants. Colette. A mineral species composed of lime carbonate. The chief constituent of many limestones. Calc-sinter. Same as Calcareous tufa. Calico marble. A name applied to the limestone conglomerate quarried near Point of Rocks, Maryland. Cellular. Containing cells, vesicles or cavities. A term most often applied to lavas. Chalk. A soft limestone, of earthy texture and usually white color. Not of much use as a building stone. Chert. A non-crystalline variety of quartz, often occurring as concretions in limestones. It is either dark or light in color and has a conchoidal or rounded fracture. China clay. See Kaolin. Chlorite. A group name for certain micaceous minerals, usually of greenish color, and being silicates containing alumina, iron and magnesia. Common in metamorphic rocks. Hardness, 2-2.7. Cipolino marble. A white marble, having veins of greenish mica. Clay. An earthy rock, having plasticity when wet, and hardening when burned. Clay holes. Cavities in stones often filled with sandy or clayey matter, which usually falls out on exposure to the weather. Cleavage. The property which some minerals and metamorphic rocks have of splitting readily in certain definite directions, which, in the case of minerals, are at a constant angle with themselves and with respect to the crystal form. Clinker brick. A very hard-burned brick. Conchoidal fracture. This applies to a curved break, resembling the curve of a clamshell. Dense rocks and some minerals often break in this way. Concretionary. Made up of concretions. Concretions. More or less rounded bodies of foreign matter found in some sedi- mentary rocks. They are often chert in limestone, and lime carbonate or iron carbonate in some clays and shales. Conglomerate. A sedimentary rock made up chiefly of rounded fragments. Also called pudding stone. Continuous kiln. One in which the waste heat from the cooling or hot chambers of brick is used to heat up the wares in other compartments still to be burned. Coquina. A limestone made up of loosely cemented shell fragments. Coral limestone. One composed of coral fragments. Such a rock is much used in the Bermuda Islands. Cresting. Trimming used on the ridge of tiled roofs. Same as Hip rolls. Crocus. A name applied to gneiss or other rock in contact with granite, in some quarries. Cryptocrystalline. Finely crystalline. A term applied to igneous rocks. 3Q2 BUILDING STONES AND CLAY-PRODUCTS Crystalline rocks. A term applied to those rocks composed of interlocking crystal- line mineral grains, which have crystallized from fusion or solution. Cut-off. The direction along which granite must be channeled because it will not split. Deck molding. Trimming made to match cresting or ridging, on clay-tiled roofs, and used for the purpose of covering the planes of a roof which has a flat deck. Decomposition. A term sometimes used to refer to the chemical breaking down of a rock on weathering. Diabase. An igneous rock of ophitic (q. v.) texture, usually fine to medium grained, and consisting chiefly of pyroxene and plagioclase feldspar. Dike. Igneous rock which has been forced into a fissure which is narrow as com- pared with its other dimensions. It may vary from a few inches to a number of feet in width. Dimension stone. Stone that is quarried or cut of required dimensions. Diorite. An igneous rock, usually of granitic texture, either fine or coarse grained, and composed essentially of plagioclase, feldspar and hornblende. Diorite porphyry. A rock of porphyritic texture, but of the same mineral composi- tion as diorite. Dip. The slope of strata, or the angle which they make with a horizontal plane. Disintegration. A term often applied to the natural mechanical breaking down of a rock on weathering. Dolomite. A mineral which is a double carbonate of calcium (lime) and magnesium. Also a rock consisting chiefly of the mineral dolomite. Down-draft kiln. One in which the heat enters the kiln chamber from the top and passes down through the ware. Dries or Dry. A seam in the rock, which is usually invisible in the freshly quarried material, but which may open up in cutting or on exposure to the weather. Dryer white. A white scum which forms on brick during drying. Dry pan. A circular revolving pan with perforated bottom, in which two large rollers revolve by friction against the pan floor. It is used for grinding dry clays. Dry-press process. A method of forming clay wares by using slightly moistened clay in pulverized form and pressing it into steel dies. Dust pressed. Same as dry pressed. Usually applied to manufacture of wall tile. Eave tile or Starters. These are roofing tile, closed underneath at the lower end. They are placed at the eave line. Enameled brick. Brick which are coated on one or two surfaces with a white or colored enamel. Encaustic tile. Floor tile having a surface pattern of one type of clay and backing of a different one. End bands. Half tile, made by cutting whole tile longitudinally, and used where the roof butts against a vertical surface. Extrusive. A term applied to those igneous rocks which have cooled after reaching the surface. False cleavage. Very fine plications, seen on the cleavage surfaces of slates. Fault. A slipping of rock masses along a fracture. Faults may occur in any kind of rock. GLOSSARY 393 Felsite. A compact, fine-grained, light-colored volcanic rock of the same mineral composition as rhyolite or trachyte, whose mineral grains are too small to be recognized by the naked eye. Feldspar. A name applied to a group of minerals having slightly different physical properties, and which are silicates of aluminum, with potassium, sodium and calcium. Thus orthoclase is a silicate of aluminum and potassium, while plagioclase is a silicate of aluminum with calcium or sodium or both. They have a pronounced cleavage and a hardness of 6. Color generally pink or whice. Very abundant in igneous and some metamorphic rocks and rare in sandstones. Ferruginous. Containing iron oxide. Ferro-magnesian. A term often applied to the dark silicates found in igneous rocks, and which contain both iron oxide and magnesia. Finial. Ornamental pieces of burned clay used for finishing off the joining of the ridge line with the hips, ridge line at gables, or top of a tower. Fire brick. One made of fire clay, and capable of standing a high degree of heat (not less than 2700 F.). Fire clay. One capable of standing a high temperature. Fireproofing. A general name applied to those forms used in the construction of floor arches, partitions, etc., for fireproof buildings. Fire shrinkage. The decrease in volume which a clay shows in burning. Fissility. The tendency which some rocks show of separating into thin laminae. Flagstone. A term applied especially to sandstones which split naturally into thin slabs suitable for flagging. Flashed brick. This term includes those brick which have had their edges darkened by special treatment in firing. Flint. This is practically the same as chert, which see. Flue linings. Pipe of cylindrical or rectangular cross section used for lining flues. Usually made of a low-grade fire clay. Flue tops. A form of burned clay ware, often of ornamental character, placed on the top of chimney flues. Flow structure. A streaked or banded structure shown by many igneous rocks and caused by a flowing movement of the rock while soft. Foliated. See Schistose. Forest marble. An argillaceous limestone in which the coloring matter is so dis- tributed as to resemble forests. Freestone. A stone that works easily or freely in any direction. It is applied especially to sandstones and limestones. Frog. See Key. Furring brick. Hollow brick for lining or furring the inside of a wall. Usually of common brick size, with surface grooved to take plaster. Gabbro. A granular igneous rock, consisting chiefly of pyroxene and feldspar. The former may predominate to such an extent as to give the stone a black color. Gable rake tile. The full-flanged tile used at the verge of open gables. Garnet. A mineral which is a silicate of alumina, lime, iron or magnesia. Its hardness is 6-7, color often red, and grains frequently rounded. 394 BUILDING STONES AND CLAY-PRODUCTS Gneiss. A metamorphic rock, having the minerals arranged in more or less massive bands or layers. It is most commonly of the same composition as granite and might then be called a granite gneiss. Other types, however, are known, as syenite-gneiss, diorite- gneiss, etc. Gneissic. Having a structure resembling that of gneiss (q. v.). Graduated tile. Roofing tile which are required for covering curved surfaces such as a round tower, circular bays and other circular roofs. Grain. A term used to indicate the second best direction of splitting. In granite it is usually at right angles to the rift; in slates it forms an angle to the cleavage. The term is also used to refer to the texture of a rock. Granite. A plutonic igneous rock, usually even granular, of either fine or coarse grain. It is composed essentially of quartz and orthoclase feldspar, and one or more minerals of the mica, amphibole or pyroxene series. Granite-porphyry. A rock of porphyritic texture and of the same mineral composi- tion as granite. Granitoid. Having a texture like granite. Granodiorite. A diorite (q. v.), carrying a considerable percentage of quartz. Graywacke. A sandstone of compact character, composed of grains of quartz, feldspar and argillaceous matter. Greenstone. An indefinite term often applied to many dark igneous rocks of a green color, the latter being due often to chlorite. The term greenstone is applied to gabbro and basalt, diabase and diorite. Grit. A sharp, gritty sandstone, especially one used as a whetstone. Grog. Ground up pieces of burned clay or brick, added to the raw clay mixture for the purpose of decreasing the shrinkage and density of the burned ware. Hardway. A direction of splitting at right angles to rift and grain. Same as Cut-off. Harvard brick. A term originally applied to clear, red, common brick, which were overburned, and especially so on one end or side, so that these harder burned parts were bluish black. The name is more loosely used nowadays. Header. A brick or stone laid with its greatest length at right angles to the surface of the wall. Heading. A term sometimes used in quarrying to apply to a collection of close joints. Hematite. A mineral which chemically consists of iron oxide (Fe2Os). Its powder is red. Hip and ridge angle. A piece of roofing tile required where a hip starts from a ridge. Hip-roll. A tile used for covering the hips on roofs, and which in cross section may show either roll or an angle. Hip roll starter. A closed hip piece of roofing tile used at the lower end of a hip roll. Hip tile. Tile which run up against a hip stringer. Holocrystalline. A term applied to igneous rocks, which are usually crystalline. Hollow blocks. These are hollow shapes, larger than common brick, usually of rectangular form, and having some cross webs. Used in exterior walls and also partitions. Hollow brick. Brick molded with hollow spaces in them. They are usually strengthened by cross webs. GLOSSARY 395 Igneous rock. One which has formed by the cooling of a molten mass of rock. Interlocking tile. Roofing tile having ridges and grooves which interlock when the tile are laid on the roof. Intrusive rocks. A term applied to those igneous rocks which have solidified with- out reaching the surface. Their occurrence on the surface now is because the rocks which were above them have been worn away. Iron pyrite. See Pyrite. Joints. Fractures, often steeply inclined, which may occur in any kind of rock. They are usually arranged in one or more series, those of the same series being parallel. Horizontal joints in granites develop a sheeted structure. Kaolin. A white residual clay (q. v.) used in the manufacture of wall tile, china and sanitary ware. Key, Frog or Panel. A rectangular depression, in one or both flat sides of a brick. Kiln white. A scum which originates in the burning of brick. Knots. A term often used to apply to bunches or segregations of dark minerals found in granites and gneisses. Sometimes applied to concretions found in sedimentary rock. Lava. A molten rock, especially one flowing out over the surface. The term is also applied to the solidified rock. Ledge. This term is usually applied to one, or a group of several beds occurring in a quarry. Also a ridge of solid rock outcropping at the surface. Lift. The name sometimes applied to joint planes which are approximately hori- zontal. Limestone. The name properly belongs to rocks composed of lime carbonate. They grade into dolomites with an increase of magnesium carbonate. Inter- mediate types are spoken of as magnesian or dolomitic limestones. Clay and quartz are common impurities. Limonite. The hydrous iron oxide commonly found in many rocks. It is usually of brownish color. Liver rock. Merrill states that this term is applied to a variety of Ohio sandstone which breaks or cuts readily in one direction or another. Lustre. The natural polish or reflection shown by the surface of some minerals. Different kinds are recognized, such as vitreous, pearly, greasy, silky, etc. Magnetite. The magnetic iron oxide (Fe 3 O 4 ). It may occur in the darker colored igneous rocks and slate, but usually in microscopic grains. Marble. True marbles are crystalline limestones, formed by the metamorphism of either limestones proper or dolomite. In the trade the term is sometimes loosely used to apply to any limestone that will take a polish. Matrix. Also called ground mass. It refers to the general body of the rock, which often has isolated crystals scattered through it. Matt glaze. A dull glaze applied to some burned clay products. Metamorphic rocks. Those derived from igneous or sedimentary rocks through the agency of heat, pressure, chemical action, or all three, acting on them when they are more or less deeply buried in the earth's crust. Mexican tile. A term sometimes applied to roofing tile of semicircular cross section. Mica. A group name of minerals which are silicates of alumina, together with potash, lithia, magnesia and iron. They show a perfect cleavage and split easily into thin elastic plates. See Muscovite, Biotite, Phlogopite. 396 BUILDING STONES AND CLAY-PRODUCTS Micaceous sandstone. One containing numerous scales of mica. Mission tile. A name sometimes applied to roofing tile of semicircular cross section. Miter ed tile. Roofing tile that are cut off obliquely, so as to fit in upright work, such as dormer corners. It also includes pieces flanged at right angles so as to cover such corners. Molded brick. A term sometimes used for soft-mud brick. Monolith. A single piece of stone. Monzonite. A rock of intermediate mineral composition between a diorite and syenite. Norman tile. Brick having the dimensions 12 by 2 j to 2 1 by 4 inches. Obsidian. A volcanic glass, usually of acidic character. Olivine. The common species is a silicate of magnesia, often of green, glassy character, and with a hardness of 6-17. It is a constituent chiefly of the darker igneous rocks such as basalt, diabase and gabbro. Onyx. True onyx is a stone resembling agate, made up of layers of silica of dif- ferent colors. The ornamental onyx or onyx marble is a carbonate of lime deposit, often colored by iron. Oolitic. Made up of very small rounded concretions, having the appearance of fish roe. Ophitic. A term relating to texture, consisting of interlacing lath-shaped crystals of feldspar whose interspaces are chiefly filled by pyroxene of later growth. Orbicular granite. A granite containing numerous rounded segregations of minerals, chiefly dark silicates. Ornamental brick. A somewhat broad term applied to front brick which are either of some form other than that of a rectangular prism, or which have the surface ornamented with some form of design. Pale brick. Brick which are underburned. Panel. See Key. Paving brick. Vitrified brick used for paving purposes. Pegmatite. A coarse-grained phase of granite. It often occurs as dikes or lenses in granites or metamorphic rocks. Peridotite. A granular intrusive igneous rock composed of olivine and pyroxene without feldspar. Phenocryst. Isolated or individual crystals, usually visible to the naked eye, which are embedded in a finer grained ground mass of igneous rock. Phlogopite. A nearly colorless mica, resembling muscovite, which is not uncommon in crystalline limestones and serpentines. Phyllite. A metamorphic rock intermediate between a slate and schist. Pipe clay. A loosely used term applied to smooth, plastic clays, but specifically referring to clays for making sewer pipe. Pipe press. The name commonly applied to the machine used for molding sewer pipe. Pisolitic. Made up of rounded concretions of about the size of a pea. Plagioclase. A collective name to include the lime-soda feldspars. See Feldspar. Plasticity. The property possessed by clay of forming a plastic mass when mixed with water. Platting. Brick laid flatwise on top of a scove kiln to keep in the heat. GLOSSARY 397 Plutonic. A term referring to those igneous rocks which have cooled some distance below the surface and show usually a granitic texture. Pompeiian brick. A loosely used term, but it is probably most frequently applied to bricks 12 by i by 4 inches in size, of medium dark shade, with a brownish body covered with iron spots. Porphyritic. A structure found in igneous rocks, indicating the presence of in- dividual crystals (phenocrysts) in a finer grained ground mass. Post. A mass of slate traversed by so many joints as to be useless. Pressed brick. A loosely used term, applied to smooth-faced brick, commonly employed for fronts. Pudding stone. See Conglomerate. Pugging. Same as Tempering. Pug mill. A machine for mixing or tempering wet clay. Pumice. A name applied to a light, porous mass of volcanic glass. Pyrite. A sulphide of iron (FeS2) easily recognized by its yellow color and metallic lustre. It weathers to limonite. A not uncommon but undesirable constitu- ent of many rocks. Pyroxene. Includes several mineral species of the same general composition as amphibole, but differing in crystal form. Its hardness is usually 5 to 6. In small grains often indistinguishable from amphibole. Quarry water. The water found in the pores of stone when first quarried. Quartz. Chemically this is silica. It has a hardness of 7, glassy lustre, conchoidal fracture and no cleavage. It is a common constituent of many igneous rocks and sandstones. Quartz monzonite. An igneous rock of granitic texture, containing quartz with orthoclase and plagioclase in about equal proportions. Quartz porphyry. A porphyritic rock having the same mineral composition as granite, and with quartz occurring as a phenocryst. Quartzite. A hard, siliceous rock, usually of metamorphic character and differing from sandstone in being harder and denser. Repressed brick. Bricks which have been put through a second pressing machine after molding, to improve their shape, etc. Residual clay. One formed by the decay of rock in place. This type is abundant in the southern states. Rhyolite. A volcanic rock of the same general mineralogical composition as granite, but which usually shows a porphyritic texture. It may be quite porous. Ribbons. Bands which show on the cleavage surface of the slate and indicate lines of bedding. Ridge roll. A curved piece for covering ridge of roof laid with roofing tile. Ridge tile. A roofing tile having the upper half flattened to a plane, and used at the roof ridge. It is covered by a finishing tile. Ridge T. Used in roof tiling to indicate a trimming piece for use at the inter- section of two ridges. Ridging. See Cresting. Rift. A microscopic cleavage in granite, which greatly aids in the quarrying of this stone. Ring pit. A circular pit in which there revolves a large wheel ; used for tempering clay. Rock-face brick. Those with surface chiseled to imitate cut stone. 398 BUILDING STONES AND CLAY-PRODUCTS Roman tile or brick. Brick usually either dry pressed or stiff -mud repressed, and 12 by 1 1 by 4 inches in size. The term is not always very definitely used. Roofing tile. Burned-clay tile used for covering roofing. Run. A term indicating the course of the rift. Saccharoidal. A texture or grain like that of loaf sugar. Salmon brick. See Pale brick. Salt glaze. A glaze seen on sewer pipe and some kinds of stoneware, produced by placing salt in the kiln fires during burning. Sandstone. A sedimentary rock, normally composed chiefly of sand grains. Sap. An iron discoloration along joint surfaces in rocks. Schist. A metamorphic rock made up chiefly of scaly mineral particles, like mica, which are arranged in a more or less parallel position and hence give the rock an irregular foliated or laminated structure. Schistose. Having the structure of a schist. Scove kiln. A temporary kiln, often used for burning common brick. Sculp. The breaking of slate preparatory to splitting. It is usually done along the grain. Seam. Same as Joint. Sedimentary rocks. Those usually deposited under water, and having a stratified structure. Selenite. A transparent crystalline variety of gypsum. Semi-dry-press process. Practically the same as dry press, but clay may be slightly moister. Sericite. A term applied to fine-grained, fibrous, white mica or muscovite. Serpentine. A mineral composed of hydrous silicate of magnesia. The same name is applied to rocks made up chiefly of this mineral. Settle. A term used to indicate the amount of vertical fire shrinkage that takes place in a kiln full of bricks. Seiver brick. A general term applied to those common brick which are burned so hard as to have little or no absorption. They are, therefore, adapted for use as sewer linings. Shale. A consolidated clay. Shaly. A term applied to thinly bedded rocks, which break up into thin layers like shale. Sheet quarry. A term often used in granite quarrying, to designate a quarry having strong horizontal joints and few vertical ones. Shelly. Same as Shaly. Shingle tile. A flat form of roofing tile. Shrinkage. The decrease in volume which clays undergo in drying and burning. Siding tile. Any roofing tile employed for upright work. Siliceous. Containing appreciable silica as an impurity; for example, a siliceous limestone. Slate. A metamorphic rock derived usually from shale and clay. It generally has a well-developed cleavage. Slickensides. Polished and grooved surfaces, caused by one mass of rock in the earth's crust sliding past another, as happens in faulting. Slip clay. An easily fusible clay, sometimes used to make a natural glaze on the surface of clay wares. GLOSSARY 399 Slip glaze. One produced with slip clay (q. v.). Slop brick. A name sometimes applied to soft-mud brick. Soak pit. A pit in which wet clay is allowed to soak preparatory to molding. Soft-mud process. A method of molding brick, by forcing clay into wooden molds. Spanish tile. Roofing tile having an S-shaped cross section. Specific gravity. The weight of a substance, as compared with an equal volume of distilled water. Stalactite. A carbonate of lime deposit formed on the roof of limestone caves. Stalagmite. A carbonate of lime deposit built up, usually in columnar forms, on the floor of caves. Starter. See Eave tile. Stiff-mud process. A plastic method of molding brick by forcing the clay through a die. Stock brick. The better or selected bricks of a kiln. Stratified rocks. Those rocks which occur in layers or beds and are of sedimentary origin. Stretcher. A brick or stone laid with its length parallel to the face of the wall. Strike. A term applied to stratified or metamorphic rocks to indicate the direction in which the tilted beds extend. Stripping. Worthless material which has to be removed in quarrying. Syenite. An igneous rock closely allied to granite, but differing from it in not containing quartz. Syenite porphyry. A rock of porphyritic texture and same mineral composition as syenite. Syncline. A trough -like fold. Talc. A hydrous silicate of alumina, magnesia and iron. Hardness i, feel greasy, and structure usually foliated. Soapstone is a massive impure form of talc, of no value as a building stone, but used for table tops, sinks, tubs, etc. Tapestry brick. These are brick made by the stiff-mud process and having all surfaces roughened by wire cutting. Much used now for exteriors. Tempering. The process of mixing clays preparatory to molding them. Terra-cotta clay. A loose term that might include any clay used in the manufacture of terra cotta. Terra-cotta lumber. A name applied to fireproofing shapes, which are very porous and somewhat soft. Toe nails. Defined by Dale as "Curved joints intersecting the sheet structure, in most cases striking with the sheets, in some differing from them in strike 45 degrees or more." Trachyte. A volcanic rock having the same mineral composition as syenite. Trap. A name often applied to diabase and sometimes to basalt. Travertine. A calcareous rock, deposited by spring or swamp waters. It is usually very porous. Tremolite. A variety of amphibole (q. v.) found as an injurious impurity in some magnesian marbles. Updraft kiln. One in which the heat enters the kiln chamber from the bottom and passes up through the ware. Valley tile. Roofing tile made to fit in the valley of a roof. Verde antique. A green rock, usually a mixture of serpentine and calcite. 400 BUILDING STONES AND CLAY-PRODUCTS Vesicular. See Cellular. Volcanic ash. A deposit of loose, fine-grained volcanic glass ejected during volcanic eruptions. In its consolidated form it may be used for building stone. Volcanic tuff. A deposit of volcanic ash which has become consolidated. Volcanic rocks. Those igneous rocks which have reached the surface before cool- ing and solidifying. Weathering. The breaking down of a rock when exposed to the action of weather- ing agents. Whitewash. A white scum of soluble sulphates which accumulates on the surface of a brick or other clay product during or after manufacture. Wall white. A white scum that appears on bricks after they are set in the wall. INDEX A. Abrasive action of wind on stone, 70. Abrasive resistance of, building stone, 70. slate, 230. Absorption of, brick, 296. building stone, 44. floor tile, 366. limestones, 181. marbles, 201. roofing tile, 355. sandstones, 163. Absorption test of brick, 296. Acids, effect on weathering of stone, 85. Adams County, 111., 191. Addison, Me., granite described, 109, in. jEolian marble, 213. Air brick, defined, 259. Alabama, granites of, 155.. limestones of, 190. marbles of, 223. sandstones of, 170. Alabama-Iris marble, 223. Alabama-Sunset marble, 223. Alabaster, defined, 10. Alfred, Me., in. Amberg, Wis., granite described, 100, IS?- American Pavonazzo marble, 213. yellow Pavonazzo marble, 214. Amherst, O., 173. Amphibole, defined, 9. Analyses of, clay, 258. limestones, 183. sandstones, 164. Andesitein, Colorado, 161. Oregon, 161. Aragonite, defined, 10. Arbuckle Mountains, Okla., granites described, 159. Arch brick, defined, 259. Architectural terra cotta (see Terra Cotta}. Arizona, marbles of, 223. onyx marbles, 250. opal marble, 223. Pavonazzo marble, 224. Arkansas, sandstones of, 176. slates of, 241. syenites described, 159. tests of slate from, 233. Arkins, Colo., 177. Arkose, defined, 29, 165. Arvonia, Va., 241. Ash, volcanic, 17. Ashlar brick, defined, 259. Athenian Green serpentine, 249. Auburn, N. H., granite described, 112. Augite, defined, 9. Ausable Forks, N. Y., granite, 137. Austin, Tex., 197. chalk, 197. Avondale, Pa., 216. B. Bangor, Pa., 238, 241. Barley ville, Me., in. Barre, Vt., granite described, 105, 116. Basalt, in Oregon, 161. characters of, 24. porphyry, defined, 24. Bate or false cleavage, defined, 226. Bathylith, defined, 17. Bayfield, Wis., 175. Becket, Mass., 100. Bedding, defined, 32. effect of, on quarrying, 32. Bedford, Indiana, limestone, 191. Beebe, cited, 298, 301, 309. Belfast, Me., in. Belfast, Pa., 241. 401 402 INDEX Bellingham, Wash., 177. Belleville, N. J., 168. Bellvue, Colo., 177. Berea, O., sandstone, 170. Berea, O., 173. Berlin, Wis., granite described, 100, 156. Bethel, Vt., granite described, 116. Bibb County, Ala., 190. Biddeford, Me., no. Biotite, denned, 8. Black granites, denned, 99. Black Island, Me., no. Blue Hill, Me., 106, no, in. Black marble, 216. Blue Hill, Me., uses of granite from, no. Bluestone, denned, 165. in New York, 168. in Pennsylvania, 169. Book tiles, denned, 333. Bosses, denned, 17. Bowling Green, Ky., 192. Bradbury, Me., in. Brandon, Vt., 202. Italian marble, 207. Branford, Conn., 100. township, Conn., granite described, 131- Branner, J.-C., cited, 176. Brecciated structure, in marbles, 198. Brick, building, raw materials used, 263. specifications for testing, 307. burning of, 279. comparison of different processes, 283. drying of, 276. kinds of, 259. methods of manufacture, 264. repressing of, 276. requisite qualities of, 314. scumming of, 312. testing of, 284. kilns, 279. Brickotta, defined, 317. Bridgeport, Wis., 195. Broad Creek, Md., 249. Brocadillo marble, 207. Brookline, N. H., in. Brookville, Me., uses of granite from, 1 10. Brownstone, defined, 165. in New Jersey, 168. Brunswick, Me., 111. Buckley, E. R., cited, 40, 43, 50, 51, 52, 55, 79, 94, 95, 155, 192. Building stone, abrasive resistance of, 70. work of wind on, 80. absorption of, 44. chemical composition of, 75. color, 37. color, change in, 38. contraction of, 69. crushing strength of, 44. decomposition on weathering, 81. discoloration, 73. disintegration of, 76. effect of acid gases on, 74. effect of carbonic acid gas on, 74. effect of careless quarrying, 80. effect of freezing on, 79. effect of plants on, 80. effect of water on, 81. effect of temperature changes on, 76. expansion of, 69. fire resistance of, 55. frost resistance of, 54. hardening on exposure, 85. hardness of, 36. life of, 86. literature on, 87. permanent swelling, 69. polish of, 40. porosity of, 40. properties of, 36. quarry water in, 44. sap of, 87. soluble salts in, 85. texture of, 36. transverse strength of, 51. weathering of, 75. Burnet County, Tex., 100, 160. Byram, N. J., 168. Cabot, Vt, 116. Calais, Me., in. Calais, Vt., 116. INDEX 403 Calcareous tufa, defined, 30. Calcite, effect of, in building stones, 10. in slate, 226. properties of, 10. Calc sinter, defined, 184. Calhoun County, Ala., 190, 223. Calico marble, 217. California, granites of, 161. marbles of, 224. onyx marbles, 250. sandstones of, 177. serpentine, 249. slates of, 242. Canaan, N. H., in. Cannelton, Ind., 174. Canyon City, Colo., 177. Carbon, effect of, on clay, 257. in marble, 198. Carbonic acid gas, effect, of, on building stone, 74. test, of building stone, 75. Cardiff, Md., 241. Carrara marble, texture, 36. Carroll County, 111., 174. Carthage, Mo., 196, 223. Castle Rock, Colo., 160. Chalk, denned, 30, 183. Champlain marbles, 214. Chapman, Pa., 241. Charlotte, N. C., 150. Chazy, N. Y., 216. Chemical composition of, building stone, 75. granite, 95. Chemical Composition (see also Anal- yses). Cherokee, Ala., 170. Cherokee County, N. C., 217. Cherokee marbles, 218. Chert, defined, 7. in limestones, 181. Chester, Mass., granite, 120, 125. Chester, N. J., 168. Chimney rock, 191. Chlorite, defined, n. Cipolino marble, weathering of, 87. Clark's Island, Me., uses of granite from, no, in. Classification of granites, 95. Connecticut, 133. Maine, no. Massachusetts, 125. New Hampshire, 113. Clay, analyses of, 258. chemical properties, 256. color after burning, 257. in slate, 229. physical properties of, 253. properties of, 253. Cleavability of slate, 229. Cleavage, of minerals, defined, 6. of rocks, defined, 30. Clinker brick, defined, 259. Coal Measures, sandstones, Alabama, 170. Indiana, 173, 174. Michigan, 174. Pennsylvania, 169. Cockeysville, Md., 216. Colbert County, Ala., 190. Cold Springs, Okla., 159. Colorado, andesite in, 161. gneisses, 160. granites described, 160. limestones of, 197. marbles of, 223. rhyolite in, 160. sandstones of, 176. Color, building stone, cause of, 37. change of, 38. variation in, 38. Color of, building stone, 37. sandstones, 163. slate, 229. Columbia, S. C., granite described, 153. Columbia Listavena marble, 214. Columbus, Mont., 176. Colusa County, Calif., 177. Common brick, requisite qualities of } 314- Compass brick, defined, 260. Concord, N. H., granite described, in. Conglomerate, characters of, 29. Connecticut, granites of, 128. marbles of, 215. sandstones of, 166. 404 INDEX Continuous kilns, 280. Contraction of building stone, 69. Con way, N. H., granite described, 112. Conyers, Ga., granites, 154. Cook County, 111., 191. Coosa County, Alabama, 223. Coquina, denned, 30, 183. occurrence, 191. Cordilleran region, granites of, 160. limestones of, 197. Cornwall, Mo., 158. Corona, Calif., 161. Corrodibility of slate, 230. Cotopaxi, Colo., 160. Cotton-rock, Mo., 196. Cranberry Lake, N. J., granite de- scribed, 138. Creole marble, 218. Cresting tile, 361. Crosby, W. O., cited, 244. Cross fracture, of slate, 229. Crotch Island, Me., no, in. granite described, 106. Crushing test of brick, 284. Crushing strength of, brick, wet and dry compared, 294. building stone, 44. floor tile, 370. granites, 94 limestones, 181. marbles, 201. sandstones, 163. Crystal form of minerals, 6. Cullman, Ala., 170. Cut-off, denned, 96. in granite, 96. Cuyahoga County, O., 173. D. Dale, T. N., cited, 94, 96, 99, in, 113, 116, 132, 136, 233. Danielsville, Pa,, 241. Dark Florence marble, 213. Dark Vein Esperanza marble, 213. Deer Isle, Me., no. Dedham, Me., in. De Kalb County, Ala., 190. Del Norte, Colo., 161. Derby, Vt, 116. Dikes, defined, 17. in granite, 99. Dillon, Mont., 160. Diorite, characters of, 23. porphyry, denned, 24. Discoloration of building stone, 73. Discoloration test, building stone, 73. Distribution of sandstones, 166. Dix Island, Me., uses of granite from, no. Dolomite, defined, 183. properties of, 10. as building stones, 178. properties of (see under Limestones). Dolomitic limestone, defined, 184. Dorset Dark Green Vein marble, 207. Dorset Mountain, Vt., 202. Dorset white marble, 208. Douty, cited, 298, 301, 309. Dover, N. J., granite described, 138. Dry-press brick, properties of, 275. Dry -press process, 275. Dummerston, Vt., 116. Dunn's Mountain, N. C., 149. Dunnville, Wis., 174. Dutch brick, defined, 260. E. East Bangor, Pa., 241. East Canaan, Conn., 215. East Cleveland, O., 173. East Longmeadow, Mass., 167. Easton, Pa., 244. Eave tile, 361. Edgecomb County, N. C., 146. Edwards limestone, Texas, 197. Efflorescence of brick, 312. Elasticity of, granites, 94. slate, 230. Elberton, Ga., granite described, 154. Eldorado County, Calif.. 242. Electrical resistance of slate, 230. Ellicott City, Md., granite described 141. Enameled brick, defined, 259. requisite qualities, 317. INDEX 405 Essex County, N. Y , 244. Etowah County, Ala., 190. marble, 218. Euclid, O., 173. bluestone, 173. Expansion of building stone, 69. Expansion coefficient of brick, 305. F. Face brick, denned, 250. Fairburn, Ga., granites, 154. Fairfield County, S. C., 100. Fall River, Mass., 120. False cleavage in slate, denned, 226. Feldspar, properties of, 7. Felsite, characters of, 24. Finials, 361. Fire brick, denned, 260. t Fireproofing, denned 333. fire tests of, 346. properties of, 334. specifications for, 345. tests of, 341. Fire resistance of, building stone, 55. granites, 95. limestones, 181. sandstones, 165. terra cotta, 328. Fire tests of, brick, 302. fireproofing, 346. Fisk Black marble, 213. Fitzwilliam, N. H., granite described, III, 112. Flagstones, Colorado, 177. defined, 166. New Jersey, 168. New York, 168. Flashed brick, defined, 260. Flexibility of granite, 94. Flint, defined, 7. in limestone. 196. Floor tile, manufacture of, 366. properties of, 365. testing of, 369. Florence marble. 208. Florentine blue marble, 213. Florida, limestones of, 191. Foerster, cited, 43. Fourche Mountain, Ark., 159. Fox Island, Me., granite described, 109. Franklin County, Ala., 190. Frankfort, Me., in. Fredericksburg, Va., granite described, 145- Frederick town, Mo., 158. Freeport, Me., in. Freestone, defined, 166. Freezing, effect of, on building stone, 79. Freitag, cited, 302, 328, 331, 337, 338, 339, 347- Frenchtown, Md., granite gneiss, 142. Front brick, defined, 259. Frost resistance of building stone, 54. Frost test of, brick, 305. building stone, artificial, 54. natural, 54. Fryeburg, Me., in. Furring blocks defined, 333. sizes made, 338. Furring brick, defined, 260. Fusibility of clay, 255. G. Gabbro, characters of, 23. of California, 161. of North Carolina, 150. Garnet, properties of, n. Gary, cited, 70, 73. Genessee, Wis., 195. Georgia, granites of, 154. marbles of, 218. serpentine of, 249. slates of, 241. German Valley, N. J., granite de- scribed. 138. Gladson, W. M., cited, 231. Glazed brick, defined, 259. Glens Falls, N. Y., 216. Gneiss, defined, 31. Gneisses, distribution in United States, 105. of Maryland, 142. of New Jersey, 137. Gouverneur, N. Y., 216. 406 INDEX Graduated roofing tile, 361. Grady, R. F., cited, 324. Grain in slate, defined, 226. Grain of granite, 96. Granite as a rock, properties of, 18. Granite City, Okla., 100, 159. Granite diorite, defined, 23. Granite Heights, Wis., 100. Granite porphyry, defined, 23. Granites, black, 99. characteristics of, 94. chemical composition of, 95. classification of, 95. crushing strength, 94. cut-off in, 96. dikes in, 99. distribution in United States, 105. elasticity of, 94. expansion of, 95. fire resistance of, 95. flexibility of, 94. grain of, 96. inclusions in, 99. joints in, 96. knots in, 96. market price of, 136. mineral impurities in, 94. of Alabama. 155, of California, 161. of Colorado, 160. of Connecticut, 128. classification of, 133. of Cordilleran area, 160. of eastern belt, 105. of Georgia, 154. of Maine, classification of, no. of Maine, 106. of Maryland, 138. of Massachusetts, 120. of Minnesota, 157. of Missouri, 158. of Montana, 160. of New Hampshire, in. classification of, 113. of New Jersey, 137. of New York, 137. of North Carolina, 145. of Oklahoma, 159. Granites, of Rhode Island, 128. of South Carolina, 150. of Texas, 160. of Vermont, 116. of Virginia, 142. of Wisconsin, 155. porosity of, 95. porphyritic, North Carolina, 149. rift of, 96. run of, 96. sheets in, 96. specific gravity of, 94. structure of, 96. tests of, 99. uses of, 105. weight per cubic yard, 94. Graniteville, Mo., granite described, 100, 158. Granville, N. Y., 238. Graywacke, defined, 166. Gregory, H. E., cited, 132. Greenbrier County, W. Va., 190. Green Island, Me., no. Greenville, Ga., granite, 154. Greenwich, Conn., granite described, 131- Greystone, N. C., granite described, 149. Groton, Conn., granite described, 116, 132. Guilford, Md., granite described, no, 141. Gypsum, properties of, 10. H. Hagerstown, Md., 190. Hallowell, Me., granite described, 106, in. Hampton, N. Y., 238. Hannibal, Mo., 196. Hardening of building stone, 85. Hardness, of building stone, 36. of sandstones, 162. Hardness scale of minerals, 6. Hardness, test of, 37. Hard vein slate, 238. Pennsylvania, 238. INDEX 407 Hardway, defined, 96. Hardwick, Vt., granite described, 116. Hartland, Me., in. Hawes, G., cited, 37. Heath Springs, S. C., granite described, i53- Helderberg limestone, N. Y., 189. Helena, Mont., 160. Henry County, 111., 174- Hermann, cited, 40. Hermon, Me., in. Hip rolls, 361. Hip roll starters, 361. Hip tile, 360. Hollow blocks, defined, 333. sizes of, 339. tests of, 340. Hollow brick, defined, 260, 333. Hollow ware, manufacture of, 333. raw materials used, 333. Holly Springs, Ga., 249. Hornblende, properties of, 9. Hudson River Bluestone, 168. Hummelstown, Pa., 169. Humphrey, R. L., cited, 56. Hunterdon County, N. J., 168. Hurricane Island, Me., granite de- scribed, 109. I. Igneous rocks, defined, 13. classification of, 18. distribution in United States, 105. texture of, 17. used for building, 93. Illinois, limestones of, 191. sandstones, 174. Inclusions in granite, 99. Index, Wash., 100. Indiana, limestones of, 191. sandstones of, 173. Interlocking tile, defined, 351. Inyo County, Calif., 224. Iowa, limestones of, 196. Iron oxide, effect on clay, 256. Iron pyrite (see Pyrite). Italic marble, 208. J. Jacobsville, Mich., 174. Jasper, Ala., 170. marble, 214. Jay, Me., in. Jefferson City, Mo., 196. Jefferson County, Ala., 190. Jointing, defined, 32. effect of, on quarrying, 32. in granite, 96. Joints in slate, 226. Joliet, 111., 191. Jones, J. C., cited, 298, 306. Jonesboro, Me., granite described, no. Jonesport, Me., no. Julien, A. A., cited, 86. K. Kaiser, E., cited, 85. Kankakee County, 111., 191. Kansas, limestones of, 196. Kasota, Minn., 195. Keeler, Calif., 224. Kennebunkport,, Me., no. Kentucky, limestones of, 192. Kettle River sandstone, Minnesota, 175- Key West, Fla., 191. Kibbe, Mass., 167. Kirby, Vt., 116. Kittatinny Mountain, N. J., 168. Knob Lick, Mo., granite described, 158. Knobstone sandstone, Indiana, 173. Knots, defined, 96. Knowles, Wis., 195. L. Lancaster County, Pa., 189. Landscape Green serpentine, 249. Lannon, Wis., 195. Lawrence County, Ind., 191. Lawrenceville, Ga., granites, 154. Lawrenceville, N. J., 168. Lebanon, N. H., in. Lee, Mass., 215. Lehigh County, Pa., 238. 408 INDEX Lemont, HI., 191. Lenox Library, N. Y. City, 87. Lepanto marble, 216. Lewis and Clarke County, Mont., 160. Lexington, Ga., 154. Lexington, N. C., 150. Life of building stone, 86. Light Cloud Rutland marble, 207. Lime, effect on clay, 256. in slate, 229. Limestone, fossiliferous, denned, 183. hydraulic, denned, 183. Limestones, absorption of, 181. as building stone, 178. characters of, 29. chemical composition of, 183. color of, 178. crushing strength of, 181. distribution in United States, 184. fire resistance of, 181. hardness of, 178. of Alabama, 190. of Cordilleran region, 197. of Florida, 191. of Illinois, 191. of Indiana, 191. of Iowa, 196. of Kansas, 196. of Kentucky, 192. of Maryland, 190. of Minnesota, 195. of Missouri, 196. of New Jersey, 189. of New York, 189. of Ohio, 192. of Pennsylvania, 189. of Texas, 197. of Virginia, 190. of West Virginia, 190. of Wisconsin, 192. tests of, 181. texture of, 178. varieties of, 183. weathering qualities, 181. Limonite, properties of, 12. Lincoln, Me., in. Lincoln County, Me., 106. Listavena marble, 208. Lithographic limestone, denned, 183. Lithonia, Ga., granites, 100, 154. Little Falls, N. J., 168. Little Rock, Ark., 100, 159. Llano County, Tex., 100, 160. Lockport, N. Y., 167, 189. Long Cove, Me., in. Lower Carboniferous limestone, Mis- souri, 196. Lower Magnesian limestone, Wisconsin, 192, 195. Luquer, L. McL, cited, 54. Lustre, of minerals, denned, 6. Lyonnaise marble, 214. M. Machias, Me., uses of granite from, no. Mackler, cited, 313. Madison County, 111., 191. Magnesian limestone, denned, 184. Magnetite, properties of, 12. Maiden Rock, Wis., 195. Maine, granites described, 106. slates of, 237. Manitou stone, Colo., 177. Mankato, Minn., 195. Mansfield sandstone, Ind., 173. Marble, defined, 184. Marblehead, Wis., 195. Marble, absorption of, 201. characters of, 31. color of, 198. mineral composition, 197. properties of, 197. strength of, 201. texture of, 198. uses of,-2oi. weathering qualities of, 201. Marbles, distribution in United States, 202. of Alabama, 223. of Arizona, 223. of California, 224. of Colorado, 223. of Connecticut, 215. of Georgia, 218. of Maryland, 216. INDEX 409 Marbles, of Massachusetts, 215. of Missouri, 223. of New York, 215. of North Carolina, 217. of Pennsylvania, 216. of Tennessee, 218. of Virginia, 217. of Vermont, 202. Marcasite, denned, 12. in slate, 230. Marini, V. G., cited, 345. Marlboro Granite, N. H., in, 113. Marquette, Mich., 174. Marshall County, Ala., 190. Marshfield, Me., no. Martinsburg, W. Va., 241. Martinsville, N. J., 168. Maryland, gneisses of, 142. granites described, 138. limestones of, 190. marbles of, 216. sandstones of, 169. serpentine of, 249. slates of, 241. Mascoma, N. H., granite described, "3- Massachusetts, granites, classification of, 125. described, 120. marbles of, 215. sandstone of, 166. serpentine of, 244. Matthews, E. B., cited, 170. McCourt, W. E., cited, 56. Medina sandstone, 167. Mena, Ark., 242. Menominee, Wis., 174. Merrill, G. P., cited, 9, 49, 54, 70, 87, 95, 166, 177, 241, 244. Metamorphic rocks, characters of, 30. Mexican tile, defined, 350. Miami, Mo., 176. Mica, effect of, on building stone, 8. in marble, 197. Micas, properties of, 8. Michelot, cited, 51. Michigan, sandstones of, 1 74. Middlebury, Vt., 202. Milford, Mass., granite described, 1 20. Milford, N. H., granite described, in, 112. Millbridge, Me., in. Millstone, Conn., granite described, 131- Mineral impurities in granite, 94. Minerals, form of, 6. hardness of, 6. in building stones, 3. physical properties of, 5. Minnesota, granites of, 157. limestones of, 195. sandstones of, 175. Mission tile, defined, 350. Missouri, granites of, 158. limestones of, 196. marbles of, 223. sandstones of, 176. Modern Spanish tile defined, 350. Mohegan granite, N. Y., 137. Monroe County, Ind., 191. Monson, Me., 237. Montana, granites of, 160. sandstones of, 176. volcanic ash in, 160. Montello, Wis., granite described, 100, 155- Montgomery County, Ark., 241. Montgomery County, Pa., 189. Monzonite, defined, 23. Moose Island, Me., no. Moriah, N. Y., 244. Mountain white marble, 208. Mount Airy, N. C., 100, 149. Mount Ascutney, Vt., 116. Mount Desert, Me., no, in. Muscovite, defined, 8. N. Nash County, N. C., 146. Newark, Vt., 116. New Bedford, Mass., 120. Newburgh, O., 173. New Hampshire, granites of, described, in. 4io INDEX New Jersey, granites of, 137. limestones of, 189. sandstones of, 168. serpentine of, 244. slates of, 238. Newman, Ga., granite, 154. Newton, N. J., 238. New York, granites of, 137. limestones of, 189. marbles of, 215. sandstones of, 167. serpentine of, 244. slates of, 238. New Ulm, Minn., 176. Niagara limestone in, Illinois, 191. New York, 189. Wisconsin, 192, 195. Normal tile, defined, 350. Norman tile, defined, 260. Norridgewock, Me., no, in. Northampton County, Pa., 238. North Carolina, granites of, 145. marbles of, 217. North Jay, Me., granite described, 105, 106. O. Oglesby, Ga., granite described, 154. Ohio, limestones of, 192. sandstones of, 170. Oklahoma, granites described, 159. Old Spanish tile, defined, 350. Olive marble, 214. Olivine, properties of, n. Olivo marble, 214. Onyx, defined, 30. marble, defined, 249. marbles, foreign, 250. in United States, 250. marble, origin of, 249. properties of, 250. Oolitic limestone, Alabama, 190. defined, 184. Florida, 191. Indiana, 191. Kentucky, 192. West Virginia, 190. Ophicalcite, defined, 243. Ophiolite, defined, 243. Oregon, andesite in, 161. basalt of, 161. Oriental Verde marble, 214. Ornamental brick, defined, 260. Orthoclase, properties of, 8. Ortonville, Minn., granite, 157. Owen County, Indiana, 191. Oxford, Me., in. P. Pale brick, defined, 260. Paterson, N. J., 168. Paving brick, defined, 260. Peach Bottom slate, 241. Peekskill, N. Y., granite, 137. Pegmatite, defined, 18. Pen Argyl, Pa., 241. Pennsylvania, limestones of, 189. marbles of, 216. sandstones of, 169. slates of, 238. serpentine of, 244. Penobscot, Me., 106. Penobscot County, Me., 106. Penryn, Calif., 161. Peridotite, characters of, 23. Permanent swelling of building stone, 69. Permeability of brick, 301. Petersburg, Va., granite described, 142. Phenix, Mo., 196. Phillipsburg, N. J., 244. Phlogopite, defined, 8. Phyllite, defined, 31. Pickens County, Georgia, 218. Picton, N. Y., granite described, 137. Pirsson, L. V., cited, 17. Pittsburg, Pa., 169. Pittsford, Vt., 202. Pittsford-Italian marble, 213. Pittsford Valley marble, 213. Plagioclase feldspars, properties of, 7. Plasticity of clay, 253. Plateau white marble, 213. Plattsburg, N. Y., 216. Pleasant River, Me., use of granite from, 1 10. INDEX 411 Pleasantville, N. Y., 215. Plutonic rocks, defined, 17. Pocahontas marble, 223. Point of Rocks, Md., 216. Polish of building stone, 40. Polk County, Ark., 241. Pompeiian brick, defined, 260. Pompton, N. J., granite described, 138. Porosity of, brick, 298. building stone, 40. granite, 95. Porphyritic, defined, 17. granite, North Carolina, 149. Port Deposit, Md., granite described, 141. Port Deposit, Md., 100. Port Henry, N. Y., 244. Post, defined, 226. Potsdam, N. Y., 167. Potsdam sandstone, Mich., 174. Wisconsin, 174, 175. Pownal, Me., in. Pressed brick, defined, 260. requisite qualities of, 314. Princeton, N. J., 168. Purdue, A. H., cited, 233. Pyrite, as coloring agent, in building stone, 39. effect of, on building stone, 12. in building stone, 82. in limestones, 181. in marble, 198. in slate, 226. properties of, 12. Pyroxene, properties of, 9. Pyroxenite, characters of, 23. Q. Quarry tile, 360. Quarry water, 86. effect of, 44. in building stone, 44. Quartz, in marbles, 198. in slates, 226. properties of, 7. Quartzite, characters of, 30. defined, 166. Quartzites, distribution of, 166. Quincy, Mass., granite described, 105, 120, 125. R. Raleigh, N. C., granite described, 149. Randolph, Vt., 116. Raymond, Calif., 161. Redbeach, Me., in. granite described, 109. Red Beds, Colorado, sandstone from, 177. Redstone granite, N. H., described, 112. Repressing brick, 276. Rhode Island, granites of, described, 128. Rhyolite of Colorado, 160. Ribbons in slate, defined, 226. Richmond, Va., granite described, 142. Ridge tile, 361. Ries, H., cited, 253. Rift, 96. Ridgefield, N. J., 168. Rion, S. C., granite described, 153. Riverside, Calif., 161. Riverside County, Calif., 161. Rochester, N. Y., 167, 189. Rochester, Vt., 116. Rock face brick, defined, 260. Rocklin, Calif., 161. Rockmart, Ga., 241. Rockport, Mass., granite described, IOO, 1 2O. Rocks, classification of, 12. definition of, 12. igneous, defined, 12. plutonic, defined, 17. volcanic, defined, 17. Rockville, Minn., 100. Rockwood County, Ala., 190. Rocky Butte, Ore., 161. Roman tile (brick), defined, 260. (roofing), defined, 350. Roofing tile, absorption of, 355. glazing, value of, 356. kinds defined, 349. manufacture of, 352. materials used, 352. 412 INDEX Roofing tile, porosity of, 352. requisite characters, 359. special shapes, 360. testing of, 359. Rosaro marble, 214. Rosiwal, cited, 37. Rowan County, N. C., granite de- scribed, 149. Roxbury, Vt., 244. Royal Blue marble, 213. Royal Red marble, 214. Royal Washington serpentine, 249. Rubio marble, 214. Run, denned, 96. Ryegate, Vt., 116. S. Sainte Genevieve, Mo., 196. Salida, Colo., 160. Salisbury, N. C., 149. Salmon brick, defined, 263. Sandstones, absorption of, 163. analyses of, 164. argillaceous, defined, 29. arkose, defined, 29. calcareous, defined, 165. characters of, 29. ferruginous, defined, 166. micaceous, 29. as building stones, 162. cement of, 162. color of, 163. crushing strength of, 163. distribution of, 166. fire resistance of, 165. hardness of, 162. Sandstones of, Alabama, 170. Arkansas, 176. Atlantic States, 167. California, 177. Central States, 170. Colorado, 176. Connecticut, 166. Illinois, 174. Indiana, 173. Maryland, 169. Massachusetts, 166. Sandstones of, Michigan, 174. Minnesota, 175. Missouri, 176. Montana, 176. New England States, 166. New Jersey, 168. New York, 167. Ohio, 170. Pennsylvania, 169. Virginia, 170. Washington, 177. Western States, 176. West Virginia, 170. Wisconsin, 174. texture of, 162. varieties of, 165. weathering of, 165. Sanitary ware, 388. manufacture of, 388. properties of, 388. raw materials used, 388. San Jose, Calif., 177. Sap, in stone quarries, 87. Schist, defined, 31. varieties of, 31. Scove kilns, 279. Sculping of slate, 229. Scumming of brick, 312. Scum on terra cotta, 328. Searsport, Me., in. Sedgwick, Me., in. Semi-dry-press-process, 275. Seneca Creek, Md., 169. Seneca Red-stone, Maryland, 169. Sericite, defined, 8. Serpentine, as building stone, 243. distribution in United States, 243. mineral impurities of, 243. Serpentine of, California, 249. Georgia, 249. Massachusetts, 244. Maryland, 249. New Jersey, 244. New York, 244. Pennsylvania, 244. Vermont, 244. Washington, 249. Serpentine, properties of, n. INDEX 413 Sewer blocks, 385. Sewer brick, defined, 263. Sewer pipe, dimensions of, 373. manufacture of, 372. raw materials used, 372. requisite qualities, 374. specifications of, 377. Shakes, defined, 96. Shale, characters of, 29. Shattuck Mountain, Me., no. Sheets, defined, 96. Shelby County, Ala., 190. Shenandoah limestone, Maryland, 190. Shingle tile, defined, 349. Shrinkage of clay, 254. Slate, characters of, 30. quarrying, 236. Slatedale, Pa., 241. Slates, classification of, 225. distribution in United States, 236. for building purposes, 225. Slates of, Arkansas, 241. Georgia, 241. California, 242. Maine, 237. Maryland, 241. New Jersey, 238. New York, 238. Pennsylvania, 238. Vermont, 237. Virginia, 241. West Virginia, 241. Slate, properties of, 226. price of, 235. properties of, 229. tests of, 233. Slatington, Pa., 238, 241. Slip cleavage in slate, defined, 226. Slop brick, defined, 263. Snowflake granite, N. H., 113. Soapstone, defined, n. Soft-mud bricks, properties of, 266. Soft-mud process, 265. Soft-vein slate, Pennsylvania, 238. Solid-porcelain sanitary ware, 388. Soluble salts, in brick, 312. in building stone, 39. in terra cotta, 328. Sonorousness of slate, 229. South Berwick, Me., in. South Brookville, Me., no. South Carolina, granites of, 150. South Dover, N. Y., 215. Southern marble, 218. South Thomas ton, Me., no. Sparta, Ga., granite described, 154. Specifications, for sewer pipe, 377. Iowa, for sewer pipe, 379. Specific gravity of, brick, 309. building stone, 40. granites, 94. slate, 230. Spruce Head, Me., in. St. Augustine, Fla., 181, 191. St. Clair County, Ala., 190. St. Clair County, 111., 174. St. Cloud, Minn., granite, 100, 157. St. George, Me., 111. St. Louis, Mo., 196. St. Peter's sandstone, Wisconsin, 174. St. Stephen's limestone, Alabama, 191. Statuary marble, 213. Steatite, properties of, 11. Stevens County, Wash., 249. Stiff -mud brick, properties of, 275. Stiff -mud process, 269. S-tile, defined, 350. Stockton, N. J., 168. Stone Mountain, Ga., granite de- scribed, 155. Stonington, Me., uses of granite from, 1 10. Stony Creek, Conn., granite described, 131- Stout, Colo., 177. Stratification (see Bedding), 32. Strength of slate, 230. Stratified rocks, defined, 24. Structural features of quarries, 31. Sturgeon Bay, Wis., 195. Sullivan, Me., in. Sulphur, effect on clay, 257. Sulphuric acid gas, effect on building stone, 74. Sulphurous acid gas, effect on building stone, 74. INDEX Sussex County, N. J., 168, 189. Sutherland Falls, marble, 208. Swans Island, Me., no. Swanton, Vt., 202, 214. Swanville, Me., in. Swain County, N. C., 217. Syenite, characters of, 23. Arkansas, 159. Missouri, 100. porphyry, denned, 23. Sylacauga, Ala., 223. Talc, properties of, u. Talladega County, Ala., 122, 190. Tapestry brick, denned, 263. Taylor's Mill, Ala., 223. Temecula, Calif., 161. Tenino sandstone, Washington, 177. Tennessee, marbles of, 218. Tensile strength of clay, 255. Terra cotta, architectural, denned, 320. fire-resisting properties, 328. manufacture of, 320. properties of, 324. raw materials used, 320. scum, 328. testing of, 324. lumber, defined, 333. Testing brick, methods used, 284. Tests for brick scum, 313. Tests of, fire-proofing, 341. hollow blocks, 340. roofing tile, 359. sandstone, 164. sewer pipe, 383. slate, 233, 234. Tests, proposed, for sewer pipe, 382. Texas, granites of, 160. limestones of, 197. Maryland, 216. Texas Creek, Colo., 160. Texture of, building stone, 36. sandstones, 162. Topsham, Vt., 116. Toughness of slate, 230. Toula, cited, 37. Tournaire, cited, 51. Tower tile, 361. Transverse strength of building stone, Si- effect of heat on, 53. Transverse test of brick, 294. Trap Rock, New Jersey, 138. in Virginia, 145. Travertine, defined, 30, 184. worked in Italy, 184. Tremolite, in marble, 198. properties of, 9. Trempeleau, Wis., 195. Trenton limestone, Ala., 190. Missouri, 196. New York, 189. Wisconsin, 192, 195. Troy, N. H., granite described, 111,112. True Blue marble, 213. Tuckahoe, N. Y., 215. Tufa, calcareous, defined, 30. Tuff, defined, 17. Tuscaloosa, Ala., 170. U. Unakite, in Virginia, 145. V. Valley tile, 360. Verdolite, 244. Verdoso marble, 214. Verdura marble, 214. Vermont, granites described, 116. marbles, varieties of, 207. marbles of, 202. serpentine of, 244. slate of, 237. Veins in slate, 226. Victorville, Calif., 249. Vinalhaven, Me., granite described, 109, no, in. Virginia, granites of, 142. limestones of, 190. marbles of, 217. sandstones of, 170. slates of, 241. Vitreous sanitary ware, 388. INDEX 415 Volcanic ash, as a building stone, 93. Montana, 160. Volcanic locks, denned, 17. W. Waldoboro, Me., in. Wall tile, manufacture, 363. tests of, 369. Wallingford, Vt., 202. Warren, Wis., granite described, 156. Warren County, Ind., 173. New Jersey, 168, 189. Warrensburg, Mo., 176. Warsaw Bluestone, N. Y., 168. Washburn, Wis. y 175. Washington County, Me., 106. New York, 237, 238. Washington monument, marble in, 216. Washington, sandstones of, 177. serpentine of, 249. Watchung, N. J., 168. Water, effect on building stone, 81. Waterford township, Conn., granite de- scribed, 131. Watson, T. L., cited, 50, 146. Waupaca, Wis., granite described, 156. Wausau, Wis., granite described, 157. Wauwatosa, Wis., 195. Weathering of, building stone, 75. limestones, 181. marbles, 201. sandstones, 165. Weisner sandstone, Ala., 170. Welch's Spur, Mont., 160. Wells, Me., no. West Chester, Pa., 244. Westerly, R. L, granite described, 100, 105, 128. West Monson, Me., 237. West Rutland, Vt., 202, 207. West Virginia, limestones of, 190. sandstones of, 170. slates of, 241. Wheeler, H. A., cited, 352. Whitefield, Me., in. Whitehall, N. Y., 238. Wichita Mountains, Oklahoma, granites described, 159. Wilburtha, N. J., 168. Will County, 111., 191. Williams, J. F., cited, 37. Wilson County, N. C., 146. Windsor, Vt., granite described, 116. Wisconsin, granites of, 155. limestones of, 192. sandstones of, 174. Wise, N. C., granite described, 149. Woodbury, Vt., granite described, 119. Woodbury, Vt., 116. Woodstock, Me., in. Woodstock, Md., granite described, 141. Woolson, I. H., cited, 303, 346. Worthy, Ind., 174. Wyoming Valley stone, Pennsylvania, 169. Y. York County, Me., 106. Yule Creek, Colo., 223. ~ THIS BOOK IS DUE ON THE LAST DATE STAMPED BELOW AN INITIAL FINE OF 25 CENTS WILL BE ASSESSED FOR FAILURE TO RETURN THIS BOOK ON THE DATE DUE. THE PENALTY WILL INCREASE TO 5O CENTS ON THE FOURTH DAY AND TO $1.OO ON THE SEVENTH DAY OVERDUE. JUL I 1935 MAY 261947 LD 21-1007-8,'34 263614- UNIVERSITY OF CALIFORNIA LIBRARY