208 E. S& Breidenbaugh—Minerals found at 
light, but gray, with a honey-yellow tinge by transmitted light. 
It is in thin folie, transparent and quite tough, with slight 
elasticity ; H.=8. e plates are compact, irregular and show 
a somewhat wavy structure. It occurs lining the wall rocks. 
Small particles of magnetite and pyrite distributed through the 
plates render it quiteimpure. Mr. OC. 8S. Hastings, of this School, 
examined this mjperal for the determination of the optical 
characters. But on account of the wavy character of the best 
specimens he could only approximate to the axial divergence, 
ing it to be from 4°-8°. Analyses gave the following 
results: 
i, Il. Il, IV. Mean. Oxygen. 
sid, 40°10 40°06 nee Gus 40°08 21.70 
Al,O, 14°21 14°21 ae = ice 14°21 7:04 
€,0, 11°51 11'51 as cea 11°51 3°35 
MgO 21°86 22°19 ea fete 22°03 8°47 
Na,O pase Sacer *39 05 22 
tee ie 9°78 9°74 9°73 1°63 
H,O chee Ms oe 1°69 1°69 1°69 1°39 
F eee a. cue Oe a tr. 
99°47 
Giving as the oxygen ratio for R, 8%, Si, 1-11: 1:21; which is 
1 | 
Chlorite—A chloritic mineral is found very mers 
it 
e 
opalescence. Between the plates are found small particles of 
magnetite. The surface plates and edges generally show ev! 
It. 1. Mean. 
SiO, 32°30. 32°86 sade 32°33 17°22 
Al,O, 14°57: 14°55 fais 14°56 6°78 
FeO 5°29 eee 5°29 117 
MgO 83°70 33°78 bigs 33°74 13°5 
CaO 1-04 1°04 cee 1°04 29 
K,0 es ‘87 87 14 
Na,O wes -~ *B4 B4 3 
12°01 12°04 ee 12°02 10°68 
100°39 
