﻿376 T. M. Chatard — Zucasite, a new variety of Yermiculite. 



a greenish tint. Luster submetallic, somewhat greasy, the 

 material having a great resemblance to the so-called " bronze- 

 powder." Easily decomposed by concentrated hydrochloric 

 acid, the silicic acid separating in pearly scales. When heated 

 gives off much water and exfoliates with considerable force, 

 particles being projected several centimeters from the mass, 

 which doubles its bulk and becomes reddish brown with a 

 silvery luster. It was examined microscopically by Mr. J. S. 

 Diller, who reports "that it is biaxial and negative, but the 

 angle between the optic axes, as seen in a cleavage plate split 

 off parallel to the base, is uniformly small. Upon rotating the 

 section, although the cross is plainly distorted into two hyper- 

 bolas, they do not completely separate from each other." 



In the following water determination the figures in brackets 

 represent differences, the others being direct determinations : 



Average. 



H 2 at 110° _ 3-87 3'81 3*72 3'72 3"78 



H 2 Oatl30°._ 0-12 ) 



H 2 at red heat (blast lamp) (6-83) [ 7*04 (6-95) (7'00) 6*98 



10-82 (10-85) 10-67 10-72 10*76 



Of the following analyses Nos. 1 and 2 are the results 

 obtained on the air-dried mineral ; No. 3 is the average and No. 

 4 the average calculated as dried at 110.' 



o 



1. 2. 3. 4. 



H 2 at 110° 3*78 (3-78) 3'78 



H 2 at 130° and r. h. 6'98 (6-98) 6*98 7'22 



Si0 2 39-89 39-74 39*81 41*17 



A1 2 3 12-881 _--- 12-99 13*43 



O 2 3 0-541 0-54 0*56 



Fe 2 3 5-29f- iyb2 iy J4 5-29 5*47 



FeO 0-llJ O'll 0-11 



MnO 0-05 0-05 0'05 0*05 



CaO 0*14 0-13 0-14 0'14 



MgO 24*88 24-78 24'83 25*68 



K 2 5-76 (5*76) 5*76 5*96 



Na 2 0-20 (0*20) 0-20 0*21 



100*50 100-46 100*48 100*00 



No. 4 gives the atomic ratio 



Si : fi : R : B : BE 

 2-75 : 1-03 : 1*29 : 0-14 : 0'80 



2*75 : 2*46 : 0*80 



•7 : *6 *2 



