.«u ^ oOj*

W>1

IMAGE EVALUATION
TEST TARGET (MT-3)

r/.

1.0

I.I

11.25

Uuu

IIIIIM

U ill 1.6

:> ?

'^^f

Photographic

Sciences

Corporation

23 WEST MAIN STREET

WEBSTER, N.Y. 14580

(716) 872-4503

L1?

^<b

o"^

'%'■

I/.

CIHM/ICMH

Microfiche

Series.

CIHIVI/ICIVIH
Collection de
microfiches.

Canadian Institute for Historical Microreproductions / Institut Canadian de microreproductions historiques

Technical and Bibliographic Notes/Notes techniques et bibliographiques

The Institute has attempted to obtain the best
original copy available for filming. Features of this
copy which may be bibliographically unique,
which may alter any of the images in the
reproduction, or which may significantly change
the usual method of filming, are checked below.

D
D
D
D
D
D
D

Coloured covers/
Couverture de couleur

Covers damaged/
Couverture endommagde

Covers restored and/or laminated/
Couverture restaurde et/ou pelliculde

Cover title missing/

Le titre de couverture manque

Coloured maps/

Cartes g^ographiques en couleur

Coloured ink (i.e. other than blue or black)/
Encre de couleur (i.e. autre que bleue ou noire)

Coloured plates and/or illustrations/
Planches et/ou illustrations en couleur

Bound with other material/
Relid avec d'autres documents

Tight binding may cause shadows or distortion
along interior margin/

Lareliure serree peut causer de I'ombre ou de la
distortion le long de la marge intdrieure

Blank leaves addbd during restoration may
appear within the text. Whenever possible, these
have been omitted from filming/
II se peut que certaines pages blanches ajout6es
lors d'une restauration apparaissent dans le texte,
mais, lorsque cela 6tait possible, ces pages n'ont
pas 6td filmdes.

Additional comments:/
Commentaires suppi^mentaires;

L'Institut a microfilm^ le meilleur exemplaire
qu'il lui a 6t6 possible de se procurer. Les details
de cet exemplaire qui sont peut-dtre uniques du
point de vue bibliographique, qui peuvent modifier
une image reproduite, ou qui peuvent exiger una
modification dans la m6thode normale de filmage
sont indiquds ci-dessous.

D
D

Pagination as follows : 7-13 p.

This item is filmed at the reduction ratio checkad below/

Ce document est film6 au taux de reduction indiqud ci-dessous.

10X 14X 18X 22X

Coloured pages/
Pages de couleur

Pages damaged/
Pages endommagdes

Pages restored and/or laminated/
Pages restaur6es et/ou pelliculies

Pages discoloured, stained or foxed/
Pages d6color6es, tachetdes ou piqu^es

Pages detached/
Pages d^tachdes

Showthrough/
Transparence

Quality of print varies/
Quality in^gale de I'impression

Includes supplementary material/
Comprend du materiel supplementaire

Only edition available/
Seule Edition disponible

Pages wholly or partially obscured by errata
slips, tissues, etc., have been refilmed to
ensure the best possible image/
Les pages totalement ou partiellement
obscurcies par un feuillet d'errata, une pelure,
etc., ont 6t6 film^es d nouveau de facon d
obtenir la meilleure image possible.

26X

SOX

12X

16X

20X

24X

28X

32X

aire
details
ues du
t modifier
ger une
I filmage

I
i^es

y errata
}d to

ie pelure,

con d

The copy filmed here has been reproduced thanks
to the generosity of:

National Library of Canada

The images appearing here are the best quality
possible considering the condition and legibility
of the original copy and in keeping with the
filming contract specifications.

Original copies in printed paper covers are filmed
beginning with the front cover and ending on
the last page with a printed or illustrated impres-
sion, or the back cover when appropriate. All
other original copies are filmed beginning on the
first page with a printed or illustrated impres-
sion, and ending on the last page with a printed
or illustrated impression.

The last recorded frame on each microfiche
shall contain the symbol ^- (meaning "CON-
TINUED"), or the symbol y (meaning "END"i,
whichever applies.

Maps, plates, charts, etc., may be filmed at
different reduction ratios. Those too large to be
entirely included in one exposure are filmed
beginning in the upper left hand corner, left to
right and top to bottom, as many frames as
required. The following diagrams illustrate the
method:

L'exemplaire filmd fut reproduit grdce d la
g6n6rosit6 de:

Bibliothdque nationale du Canada

Les images suivantes ont 6t6 reproduites avec Ie
plus grand soin, compte tenu de la condition et
de la nettetd de l'exemplaire film6, et en
conformity avec les conditions du contrat de
filmage.

Les exemplaires originaux dont la couverture en
papier est imprimde sont film6s en commenpant
par Ie premier plat et en terminant soit par la
dernidre page qui comporte une empreinte
d'impression ou d'illustration, soit par Ie second
plat, selon Ie cas. Tous les autres exemplaires
originaux sont filmds en commenpant par la
premidre page qui comporte une empreinte
d'impression ou d'illustration et en terminant par
la dernidre page qui comporte une telle
empreinte.

Un des symboles suivants apparaitra sur la
dernidre image de cheque microfiche, selon Ie
cas: Ie symbole — ^ signifie "A SUIVRE", Ie
symbole V signifie "FIN".

Les cartes, planches, tableaux, etc., peuvent §tre
filmds d des taux de reduction diffdrents.
Lorsque Ie document est trop grand pour dtre
reproduit en un seul clichd, il est film6 d partir
de Tangle supdrieur gauche, de gauche d droite,
et de haut en bas, en prenant Ie nombre
d'images ndcessaire. Les diagrammes suivants
illustrent la mdthode.

32X

Section IV., 1884.

[ 7 ]

Trans. Roy. Soo. Canada,

II. — Notes on the Manganese Ores of Nova Scotia.

By Edwin Gilpin, .Tun., A.M., F.G-.S.

(Read May 22, 1884.)

In the following sketch I have endeavoured to bring together the information relative
to the manganese ores of Nova Scotia. The only previous note now accessible, beyond
the references in Dr. Dawson's " Acadian G-eology," is one by the late Dr. How, of King's
College, Windsor, published in the Transactions of the Nova Scotia Institute of Natural
Science. The exceptional purity of some of the ores makes them interesting to the
mineralogist, and valuable in certain operations of the manufacturer. The attention paid
in Nova Scotia to the working of these ores is by no means proportionate to their value,
and to the great extent of the geological formation to which they appear to be chiefly con-
fined. The object of these notes will be obtained, if they serve to indicate that the ores
of manganese may prove in the future an important addition to the mining resources of
this province.

The least valuable but certainly the most common of the Nova Scotia manganese
ores is wad. This ore is found as a superficial deposit in connection with cA'ery geological
formation known in the province. Among the localities yielding it may be mentioned
Jeddore, Ship Harbour, St. Margaret's Bay, Shelburne, La Have, Chester, Parrsborough,
Spriiighill, Pictou, and Antigouishe. These ores exhibit the varying corapositiou which
characterizes their class, and ha\ e in some cases been used to a limited extent as paints.
On Boularderie Island, Cape Breton, a bed of wad, several feet thick, was examined some
years ago. The following analyses show this want of uniformity of composition: two
analyses by Mr. Hoffman, of the Canadian Geological Survey, gave : —

Manganese peroxide 25-42

Iron sesquioxide —

Insoluble matter —

Water 33-52

II.

11-04
12-49
57-76

also, in the case of analysis II, traces of copper, cobalt, and nickel.

An analysis, by the writer, of a sample from a different part of the bed, gave ;

Manganese peroxide 44-33

Iron sesquioxide .3.5-50

Insoluble matter. 10-00

At the Londonderry Iron Mines, Colchester County, in the great vein of brown
hematite, associated with ochre, ankerite, siderophisite, and calcite, in strata of Lower
Silurian age, secondary changes have at some points enriched the iron ore with manganese

EDWIN (illiPIN ON THK

peroxide up to fourteen per cent, of its total conHtituents. Some encrusting fibres aro

nanganite, and part of the manganese is present under the form of wad, of which Mr.
li Lonis gives the following analysis : —

Manganese peroxide G7-10

^langaneso protoxide 10-67

Water 9-37

Copper protoxide -88

Iron protoxide 4 09

Alumina. '07

Nickel and cobalt oxide •05

Lime 2'49

Magnesia trace

Silica 4-08

100 '00

The occnrronco of this ore in the pre-carboniferous rocks is interesting, as showing
its original wide distribxition, and as possibly indicating the sources of part of the more
recent ores of economic Aalixc. Pyrolusite is the only ore of manganese which has hitherto
been mined to any extent in Nova Scotia, and it is known to occur in pre-carboniferous
strata at several points. Between Halifax and Windsor, near Mount Uniacke, pyrolusite
IS foimd in small pockets and veins penetrating granite, and in quartzitcs of the auriferous
Lower Cambrian of the Nova Scotia Atlantic ci/ast. It occurs in veinlets in the <rranite
of Musqixodoboit, and as small irregular seams in the granite of Ship Harbour. In the
hills soiith of Wolfville, in King's County, the same ore is found in quartzitcs and slatt>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.

Lime carboiiato

Iron carbonate

Magnesia carbonate . . .
^Manganese carbonate.

Insohiblo matter

Moisture

Si)rinf,'villo, (IMcton Co.) Tenny f'aiio Pnhnoii River, C. B.

II.

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.

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-fra<iures. It thus occurs that large
masses almost entirely isolated have been met, also seams with occasional pockets, some-
times connected, but in no case, so far as I nm aware, following any regular order of
position or extent. The largest mass yet found wiis estimated to coninin 180 tons of ore.
Apparently, the ore has beini deposited at irregular int<>rvals 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 <br their freedom from im]mriiies, especially of iron. This
high grade of the pyrolnsite from the; Teiniy Capt? district will a])pear when, from
niimtu'ous assays, it has been found to yield from eighty-eight to ninety-livi' per cent, of
available oxide. The following analyses show the general character of these ores : — .

Douglas. '

Moisture 1-OCO

Water of composition 3 • 630

Iron peroxiao -603

Oxygen 7.035

liaryta

Insolul)lo matter

I'liospliorie acid

^Manganese oxides

Peroxide of manganese

Lime

100-000

<'lioverio.
2-05

2-55

•724

1'12

1 • 728

2-80

—

1-029

S4-020

—

00 -15

—

trace

99-099

At Walton and Cheverie manganite is more common than at Tenny Cape. Its mode
of occurrence is similar, and its general character is shown by the following analyses : —

' Contains some psilomelane ; analyst, H. Poole.
'^ K. Gilpin.

MAGANRSK OTJKS OF NOVA SCOTIA.

unci may
south of
of their
Lt'iint'se of
imcsfoiu',
ru ond of
mt'stoncs

lavo bt'on
I'm to ]w
H, ami in
lat hirg'o
'ts, somo-
ordov of
IS of ore.
issoi'iatt'd
nous may
iurroiiud-
a li broils
r of pyvo-
ircscut ill
H' rcc^'ivo
»'. They
)n. This
(Ml, iVom
rout, of

Its mode

yscs :~

Toniiy. '

MniigaiHw^ oxiduH 85 54

Iron |)*trnxi(l« l'18-»

Harytft. . -SO /

IiKsolublij matter 3 27

I'lioHphuric aciil -34

AVator 8-54

Availal)lo oxyjion 51 -54

C'hovorio.

St) 'SI

2.05
114

10-00
47-73

The Toimy Capo manganitf! is compaot, with partly fibrous structure, and submc-
tallic lustre. It is not in much demand at present, but I am informed that considerable
quantities could be got at several points. The following art; the principal minerals found
in connection with the Tenny Capo ores : —

CaJdte. This, the most abundant accessory, occurs as low rhombohedral crystals
implanted on the limestone, of reddish and bluish shades, frequently with the edges
'•louded symmetrically with imi)urities ; and as a secondary deposit on the preceding
crystals, in the form of snow-white grannular incrustations, frequently penetrated by the
fibres of pyrolusite ; and as a cd^ ping on isolated fibres of the ore. The p''"olu8ite also
occurs encrusting wine-coloured crystals o.*" dog-tooth spar. •

Iron is present as an earthy red hematite, and as a fibrous and mammilatcd limonite.
Iron sulx)hide is seldom visible.

Barite occurs in rounded nodules, and in tabular crystals in the ore, and mixed with
the calcspar.

Selenile is soinetiiues noticed in fibrous form, and in thin transparent films.

Many very beautiful cabinet specimens of these minerals have been met at Mr. J. "W.
Stej^hens' mine, the natural beauty of the crystals being greatly increased by the setting
of gleaming fibres of the black pyrolusite.

Lower Carboniferous limestones at Minudie, in Cumberland County, have yielded
small quantities of a soft fine-grained pyrolusite, giving on analysis OtOi per cent, of
manganese binoxide. Ores similar to those of Tenny Cape arc found at Onslow, and ou
the Salmon River, near Truro, Colchester County. Prospecting work has shown red
shales and sandstones, and beds of dark-bluish limestone, covered by beds of gravel and
clay holding nodules of compact sub-crystalline pyrolusite. The ore also oc<urs in veins,
up to four inches in thickness, in the sandstones, and in irregular nests and layers in the
limestone. Calcspar, barite, and selenite are found in the veins, which are filled with
iibroiis ore. The exact horizon of the beds holding these ores is not readily ascertainable,
and it may l)e higher in thi' marine limestone formation than at Tenny Cape. The ore is
of very goo'1 qualiiy, some, of it running as high as ninety per cent, of available oxide. In
Pictou County, near Glengarry station, nodules of librous pyrolusite, containing eighty-
four per i'lUit. of peroxide, are found with crystals of dog-tooth spar, in a dark-blue lime-
stone, similar to that at Springville already referred to, and exposed close to the junction
of the marine limestone with pre-carboniferous iwks.

Boulders of a mixture of psilomclane with manganite occur lying on the limestone
at Springville, of which an analysis has already been given, and on the associated red

' Dr. How.
■' E. Gilpin.

Ifi

KDWIN (IIMMN ON TIIR

8halos. Ai Hcvt'iiil poinlM in lliis vicinily <h"' liinonilc nvt's, louiid iiloiiijf tin- line of junc-
lion ol" llio Upper and Lower Siluriiiii willi the Lowt-r ('arboiiircrous mariiit^ linu'stoiio
aro heavily charycil wit li niaiij-iuit'Hf. The ore is dull hrownish-lilnck in colour, with a
l)la(;k streak, and nol'ter than the normal limonile. The percenlai?e ol' nian<jani>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.

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.