370 Ninth Supplement to Dana’s Mineralogy. 
= Jarge crystal measuring six by four inches. The mineral is yellow biaxial ; lam- 
z less flexible than chlorite, almost brittle; color. Fess game low.  light-yellow by 
tranemitted light. Snort gravity of the air-dried mineral Hardness, 
between gypsum and com salt, B.B. in forceps exfoliates woe meas pearly 
white and opa no and bt prokilied heating fuses to a dark gray mass. In close sed 
tube exfoliates, frequently. meee * om heated tube, and gives off water which re- 
acts alkaline. With the fluxe xes gives reactions for silica and iron. Decomposed b 
chlorhydric acid. The air-d suiode 419 pr. ct. in weight by dry ape - a sul- 
phuric acid desiccator, and 3°74 r. ct, additional when dried at 100° C G, ted in 
an air-bath to baoe C. it lost 417 ve. ct., but between 220° and 300° C. the ies was 
maa 
5 pr. = peck i ait ssum 
cuphuri acid to have been —— “9 mie we baie 18° . r. ct. of water 
od 
fs included as essential, but it is ct ai safest to take the mineral as dried over 
Si AL Pe 6 6fe 6 6CallCUMg «CKO H 
8710 1757 1054 126 056 19°65 043 tr. 18-76 = 100°87 
Other analyses ange in 1853 by Prof. Smith and myself gave similar results. ara 
iron in the mineral has und 
oubtedly been partially oxydized As weathering, many of 
the e infiltration of foreign matter between the ieikines and 
hey are quite friable from exposure. belongs to the chlorite section of magnesian 
hydrous silicates in view of its pyrognostic properties we refer it with a quer 
ermiculite, which its chemical composition approxim great difficulty 
of obtaining pure vermiculite in sufficient quantity for analysis has thus far pre- 
vented me from way wee it, in fact I have delayed publishing my results on the 
Weschester mineral for more than two years, hoping thereb to be able to ee’ 
mine more fully its iotakiong to this species. The oxygen ratio for the Si, #, R. 
as Calculated from the analysis is as 19°89 : 11°86 :8°36:11:28 or 7:4:8: e "equal 4 
3k*Si+ 4Si+-192 oft e more general expression (R*#) Si+-Aq. The mineral 
and so liable i 
to 
hlorite 
The chief ss ade in goers. it here, is a call attention ° its re- 
cape of hygroscopic i alabtore, as it Figs ot take place to ‘any ¢ considerable degree 
until the mineral is exposed to a temperature above 300° C.— 
Water [p. 11 Mare ro Dufour has found the density of ice 9° C., to be 0°9175. 
—( Comptes "Rendus,1, 39.) 
Wuarrserire [VII]. =p ie bape has were (L. #. & D. Phil. Mag, (4), 
423,) under the name darwi an arsenid of copper typi is identical in pupéeal 
and chemical properties with Genth's whitneyite. It is stated to occur i ae near 
Potrero Grande near Copia’ e. It is massive, without cleavage, ra tle, 
but ast Soe be distinetly impressed by the vm ammer : frac e uneven; lustre ‘etalie; : 
color of fresbly-fi e dark silver-gre y, one e dirty coast tara : 
streak shetalia: edo ig ; Opaque. H. be 5. G.=864, BB. gives reactions 
copper and arsenic with trace of silver. Composition: 
i, se 3. 4, 
Cu 88°35 88-07 ee Sk | 88°02 
Ag 0°38 0-24 | 0:08 0°42 
As 11:27 11°69 1181 1106 
[These Wilt leave no doubt as to the identity of the mineral th whitneyite 
pe Ao sie VIIL) fo = which Genth obtained reagan og a tad ft 8 
