.«u ^ oOj* W>1 IMAGE EVALUATION TEST TARGET (MT-3) 4p /- r/. x9 ^- 1.0 I.I 11.25 Uuu IIIIIM U ill 1.6 V] <^ /^ / ^ :> ? WA '/ '^^f Photographic Sciences Corporation 23 WEST MAIN STREET WEBSTER, N.Y. 14580 (716) 872-4503 L1? V iV \\ ^s, presumably of Upper Silurian age. In the trias of the same county, the ore is met in a bedded form near Cornwallis and "Wolfville, and in the triassic trap it is said to occur lining cavities, in association with zeolites, etc. "VVe, however, find these ores most abundantly in the LuvV^r CiiTboiilierous marine limestone formation. This horizon forms one of the widest spread, and most strongly marked of the divisions of the Carboniferous period. It is met in King's County, in Hants, Cumberland, Colchester, Pictou, and Antigonishe, and in the four counties of the Island of Cape Breton. The measiires of this division, comjirising sandstones, shales, grits, and limestones, with beds of gypsum and marl, sometimes rest directly on the pre- carboniferous strata, and at many points are separated from them by the lower, or false coal-measures, or by beds of conglomerate, according to the conditions of the period of accumulation. The limestones and gypsums occur, apparently, at no fixed horizon in this division. Dr. Dawson, in his "Acadian Greology", has divided the limestones into five groiaps, characterized respectively, so far as the subject has received attention, by a pre- dominance of certain fossil forms. In his supplement to the second edition, he proposes to subdivide the lowest group by distinguishing a certain manganiferous limestone, which appears at mar.y points to form the basis of the limestone formation, strictly so called. This limestone at Salmon lliver, Cape Breton County, Spriugville and New Laing, Pictou County, Chester, Maitland, Tenny Cape, Windsor and Onslow, seems to underlie the gypsum beds, and generally to be associated with manganese. The following analyses by the writer show the haracter of some of these limestones : — MANCJANKSE OltES OV NOVA SCOTIA. 9 Lime carboiiato Iron carbonate Magnesia carbonate . . . ^Manganese carbonate. Insohiblo matter Moisture Si)rinf,'villo, (IMcton Co.) Tenny f'aiio Pnhnoii River, C. B. T. II. I. I. 83 -42 55-28 40-81 49-2(59 120 24-11 2-56 4-044 10 -32 10-15 35-44 28-034 1-38 1-83 4-58' 14-580 4 '85 5-00 S-OO 1-298 — -40 •37 — 101-17 90-77 100-83 97-231 Tho limcsiouo of CJn'sttM-, on the Atlantic shore, presents a. remnant of Lower Carboniferons nieasnres, formerly withoiit donbt co-extensive with those of our northern counties. The lower beds are di^scribed by the late ])r. How as compat-t, of a dark blue colour, and consisting principally of carbonates of iron, lime, magnesia and manganese, yielding umbers by weathering. Thesi' are the most highly magnesian and mangan- iferous limeston(>s that J have yet mt^t in the province. It is quite possible that there may be others higher in tin; marine liraestoui^ formation carrying notable percentages of the carboiiates of these metals. In the case of the Pictou district, however, the overlying limestones, up to what may bo termed the base of the millstone-grit, are decidedly non- magnesian ; the inspection of a very complete set of analyses showing none cari/ing over four ])er cent, of the carbonate of magnesia, and usually little more than traces of manganese. The following analysis, made at the Durham College of Science, of a limestone lying abovt^ the Springville gypsum, shows the usual composition of the purer grade of the limestones of the higher si'ctions of the I'ictou marine limestones : — Lime carbonate 00-26 .^[agnesia carbonate 2-33 Iron poroxiile . . • -57 ^langanoso i^roxide -53 Alumina -10 Sulphur -02 rhcspboric acid -03 Silica 1-99 Moisture -17 101-02 In the northern part of Hants County, the carboniferous marine limestones and the underlying lower coal measures are found in a series of east and west folds, shifted and broken by transverse subordinate ilexiires. The presence of manganese in the upper of these divisions is first observable at tho mouth of th(^ Shubenacadio River, where a dark- coloured limestone xinderlics (he gypsum, and is associated, a short distanced east of the river, with red shales, carrying veins of red hematite, with manganese oxides and calcspar. The westward continuation of this horizon is noticeable again at Tenny Cajie, where a series of these measures, extending to W.alton and Cheverie, a distance of aboitt fifteen As iioriixiile. tfec. IV., 1S84. 2. 10 KDWIN (JILIMN ON TllH milos, rontuins sovcral bcdw of limostoue, which apparently iinderlif Iho gypsum, mid may 1)0 callod manganilerouH. Those mcasiiros carr3Mng mangancHo ro-ai)pt'ar again Kouth of Windsor, and at Donglas, (iftoon miles soixth of Tenny Cape, near the line of their jnnction with the pri'-eiirhoniieronN rocks. In this range of measures the miingauese of Tenny Cape api)ears to bo ])rinoipally connected with a compact red and gray limestone, which, from the analysis already given, may be callod a dolomite. At the western end of the district it occurs as veins in conglomerates and sandstones, and also in limestones iu places decidedly magnesinn. The Tenny Capi; manganese ores were discovered about the year 18(i2, and have b(>en intermittently worked sinc(! that date. The limestone band to whidi they seem to be principally confined is about 300 feet thick. Tht^ ore 0(X'urs in irregular nests, and in seams eroded on the bodding-idani's and cross-frarvals of time, with tlu? associated minerals, in the openings worn by tht! action of water on the limestones. Specimens may be obtained showing pyrolnsite, cementing waterworn i>ieces of limestone, and surround- ing nodules of the bed-rork which have resisted erosion. The ore is chielly a librous pyrolusite, with splendent lu.stre, based on a compact or granular ore consisting of pyro- lnsite, of psilomelane, and of manganite, the latter mineral however not being present in large qiiantity. The quality of these ores, even after thi' slight hand-dressing they receive at the mines, is V(ry high, and in some years they bring i§l2").00 a ton at the mine. They are prized by glas.s-makers
ise pn^sent in the iron ore , arieH. The general character of this ore, however, will npi>ear from lh« following unalyHes by tho writer : — L II. Wator (if roinposition — ^ i.i ron MoiHturo 1.450 > Insolnblo roHiduo , 2'7;U 25'i;Ji) Alumina 2'({80 traco Jrou .so8(iuiuxi(lo 10848 4«'JL'3 AIaiiv'aiu>8o si^qiiioxido fi2-!tr)() — iMaiiKaiuvin jKiroxido — 14 •110 Majiiiosia l-OiiO — Limo 7-280 -Oir) Baryta -flTO — Carbonic acid — — S.ilpbur — -480 I'liosplioruH — -OL'O !)0-439 100 '808 lu Antigonisho County similar fcrriftirous manganese ores have been found in drift at several places. In Cape Breton deposits of economic value occixr only in the western part of the county of tho same name. Here, at tho head waters of tho Salmon River, tho lower members of tho C'arboniferous are met in a valley between the felsites of the Mira and East Bay hiJls. The sjiaco is generally occupied by the millstone grit, beneath the edges of which the marine limestones occasionally crop out, or the latter are excluded by the basal conglomerates. The ibllowing notes are from a visit to the Moseley (iron) mine, and from information kindly furnished by Mr. Fletcher, of the Canadian Geological Survey. 'i'lie felsites of tho Mira Hills form a series of bays along which arc exposed carbon- iferous limestones, conglomerates, shales, and grits as they were accumulated subjec^t to the varying conditions of the winds and currents of the period under consideration. At some points, the limestones r(>st on the felsites ; at other localiti(>s, grits and shales inter- vene ; elsewhere, the basal conglomeraies are covered directly by the millstone grit. The manganese ores were discovered two years ago in one of these recesses where the felsites were sii(;ceeded by shales and grits, and finally by limestones, the iaiter apparently extending from point to point of the ancient bay. The ores at the western mine arc found in irri^gnlar bedded layers in a soft arenaceous reddish-coloured shale, whicli is in some places calcareous and coated with iilms of manganese oxide. The layers vary in thick- ness np to eighteeii inches, and are IVecjnently connected by cross stringers of ore. The shales when weathered present the ore in small nodiiles, and the disintegration of the former by water probably indicates the source of the beds of gravel manganese ore found lying on them. The ore at the eastern mine occurs as a bed immediately iindcrlying a layer of black raanganiferous limestone, with red and greenish shales and coarse grit. The thickness of the ore and limestone varies from two to eight inches, the aA'^erage thick- MAOANKSl-: OIIES OF NOVA SCOTIA. 13 nc of junc- ! liiufstono Diir, with a i'S(i l)r('.st'nt ir IVoiu Iho d ill drift art of the tho lower I Mira and the edges led by the mine, and Survey. hI car])on- subjei^t to ation. At ales inter- j^rit. The le felsites pparently are found s in some r in thick- ore. The ion of the ore found Icrlying a )arse grit, age thick- neHS of the two being ub(Uit «'ight iiichcM. The ore also otMurs in thiH vicinity ais ii-n- ticulur pocketH and irregular nents in conglomerale, etc., and HonieiimeH forms tho eenit'nting malcrial. Tliis hiltcr niodn of oicurrenee i.s similar to tluit shown by Iho rod hematites (sometimt's highly manganiffous) found at various points in the lower Carbo- niferous conglomerates of the island nt'ar their junction with older strata. The analy-is of tho overlying limestone Invs already been given. The ore from this locality /« generally a pyrolusite, soft, fine-grained, and sometimes sub-crystallino. It is at soimo openings mixed with mangnnitc, and the latter ore is abundant at several places in the grits. The minerals assot;ialed with the ore are calcsjiar, barile, lilms of selenite, and limestone. Analyses by Mr. llolfman, of the Canadian Geological Survey, show that the ores run as high as 889 per cent, of binoxide, and contain an admixture of ferric oxide as low as two-tenths of one per cent. On the Magdalen Islands, tho manganese ores are found, aci'ording to Mr. Richardson ( Gi'ological Survey Report, 18*79-80 ) associated with sand, clay, gypsum, and doleritic rocks of Lower Carboniferous age. From Mr. Ilolfman's report, (ihifl.) the ore is a purely crystalline manganite, yielding on analysis 45'61 of binoxide. I have, however, seen samples of pure pyrolusite from these islands. There do not seem to bo any limestones directly connected with these ores, as surveyed by Mr. Richardson, and the locality ajipears to form an exception to the rule which, so far as my inforn. 'tiou goes, governs the presence of manganese ores in the Carboniferous of Nova Scotia, viz., the i)resenco of limestone. rossil)ly in the case of these Magdalen Island ores they may have been derived directly from the dolerite. From the preceding notes, which (!over, I think, all the localities known to yield manganese in this province, it may be inferred that in Nova Scotia there appears to bo groiand for referrint; iho principal deposits of the ores of manganese to an horizon low down in the Carbonii v' marine limestones, and certainly, in most cases, underlying the lowest gypsum bed that limestones, magnesian and sometimes also manganiferous, appear to bo associalrd , !i them. I am not prepared to attempt any outline of the pro- cess which, in Nova Scotia, appears at some points to have deposited in these strata iron or(>s, sometimes manganiferous, and at other points ores of manganese frequently very free from iron. The source of the manganese may Ik; looked for in the older strata bordering the Carboniferous sea, or, as Dr. Daw^son suggests, its presence in these limestones may bo due to the decomposition of volcanic debris proceeding from the contemporaneous igneous vents which produced the Carboniferous traps. lloth the older bordering strata, and the limestones and associated strata may have been drawn upon for the deposits of this interesting and \is(>fi;l mineral. The action of magnesian thermal springs may have led to the alteration of thi^ limestones more particularly referred to in the preceding notes, Such an ac^tion might lead to the deposition of manganese and iron oxides, as well as of lead and copper ores, all of which are frequently found in 1h(>m.