NEW YORK. 
73 
slate, as seen under both ordinary and polarized light, see Nineteenth Annual Report 
U. S. Geological Survey, part 3, PL XXVIII, A, B, C. For a discussion of the 
causes of the green and purplish spots, which occasionally occur in this slate, see page 
15 of this bulletin. Associated with the red slate is generally a little purplish slate, 
sometimes speckled, but of no commercial importance. Under the microscope it 
shows less hematite and possibly more chlorite. Analysis N, below, shows that it 
contains from 2\ to over 4 per cent less hematite and about one-third of 1 per cent 
more ferrous oxide than the red. 
The following analyses were made in the chemical laboratory of the United States 
Geological Survey, the complete analyses by Dr. W. F. Hillebrand, the partial ones 
by Mr. George Steiger: 
Analyses of red slates from New York. 
Si0 2 (silica) 
TiOo (titanium dioxide) .. 
A1 2 3 (alumina) 
Fe 2 3 (ferric oxide) 
FeO (ferrous oxide) 
MnO (manganous oxide). 
NiO (nickelous oxide) 
CoO (cobaltous oxide) 
CaO (lime) 
BaO (baryta) 
MgO (magnesia) 
K 2 (potassa) 
Na 2 (soda) 
Li 2 (lithia) 
H 2 (water below 110° C). 
H 2 (water above 110° C) . 
P 2 5 (phosphoric oxide) .. 
C0 2 (carbon dioxide) 
FeS 2 (pyrite) 
S0 3 (sulphuric oxide) 
C (carbon) 
Total 
S (total sulphur). 
Specific gravity . . 
Specimens, a 
67.61 
.56 
13. 20 
5.36 
1,20 
.10 
Trace? 
Trace? 
.11 
.04 
3.20 
4.45 
.67 
Trace. 
.45 
2.97 
.05 
None. 
.03 
Trace. 
None. 
100. 00 
.016 
K. 
67.55 
.58 
12.59 
5.61 
1.24 
.19 
Trace. 
Trace. 
.26 
.31 
3.27 
4.13 
.61 
Trace. 
.40 
3.03 
.10 
.11 
.04 
Trace. 
None. 
100. 02 
.02 
56.49 
.48 
11.59 
3.48 
1.42 
.30 
Trace. 
Trace. 
5.11 
.06 
6.43 
3.77 
. 52 
Str. tr. 
.37 
2.82 
.09 
7.42 
.03 
Trace. 
None. 
100. 38 
.016 
2. 7839 
M 
63.88 
.47 
9.77 
3.86 
1.44 
.21 
Trace. 
Trace. 
3.53 
.05 
5.37 
3.45 
.20 
Str. tr. 
.27 
2.48 
.08 
5.08 
Trace. 
None. 
100. 14 
K.2 
7.10 
1.00 
2. 80S5 
1.02 
1.67 
a J (=D. XIV, '95, 358d), red slate, H. H. Matthews's quarry, 1 mile west of Poultney, in Hampton, 
Washington County, New York; K ( = D. XIV, '95, 201e), red slate, Empire Red Slate Company's 
quarry, 1 mile north of Granville, in Granville, Washington County, N. Y.: L(=D. XIV, '95, 397e), 
red slate, National Red Slate Company's quarry, 1 mile north-northwest of Raceville, in Granville, 
i Washington County, N. Y.; M (=D. XIV, '95, 397a), red slate, same locality as L, but near a green and 
'purple spot; K 2 ( = D. XIV, '95, 201/0, red slate, same as K, but finer grained; N ( = D. XIV, '95, 284a), 
ipurple bed in red slate at Fair Haven Red Slate Company's quarry (not worked), two miles north of 
Truthville, in East Whitehall, Washington County, N. Y. For presence of chromium and vanadium 
lin these see Doctor Hillebrand's note, p. 41. 
Some points in these analyses are discussed by Doctor Hillebrand on pages 39-42. 
As these red slates do not discolor and yet show a considerable amount of carbonate 
under the microscope, and as the discoloration of the Vermont "sea-green" slates is 
due to the oxidation of a ferrous carbonate, it may be inferred that the carbonate 
here is chiefly one of lime and magnesia, but the effect of a very small percentage of 
iferrous carbonate would probably be masked by the brightness of the hematite. 
J. F. Williams reported for this slate a modulus of rupture of 7,310 pounds per square 
■inch, and Merriman 126.66 foot-pounds of work per pound of slate as a result of impact 
tests. Th.3 results of Merriman' s recent other tests of this slate are given on page 123. 
