722 The American Naturalist. [August, 
identified in the region within the past two years. Among these is 
ottrelite from certain phyetites occurring at an old copper mine near 
Liberty, Frederick county. The crystals of the mineral are arranged 
nearly perpendicular to the cleavage planes of the rock. Their mor- 
phological and optical properties leave no doubt as to their true nature. 
In addition to the minerals described by Williams, Mr. Gill" describes 
two very rare chromium minerals found in the dump heaps of the 
chrome pits in Montgomery county. The first is a chrome tourmaline. 
This occurs in fissures in chromite, and is generally associated with 
fuchsite, both usually being imbedded in a chloritic matrix. The 
tourmaline is in the form of long dark green needles, exhibiting marked 
dichroism in green and straw-colored tints, and a beautiful zonal struc- 
ture. The fuchsite is in little green scales, whose optical angle in air 
is 68° 1 6' for sodium light, and pleochroism : A:=:robin's egg blue, B= 
yellowish green, C=bluish chrome-green. Analyses of the two min- 
erals, made by Dr. Chatard, are given below. I. is that of the tour- 
maline, II. is the analysis of the fuchsite. 
SiO., B,0, Fl P.O. TiO, ALO, Cr,0, Fe.,0. NiO CaO 
Analyses and short descriptions of thre 
communicated by Dr. Genth ;i8 Gadolir 
counties, Texas, has a black color, is trai 
has a greenish gray streak. Analysis c 
22.87 
A1,0, 
Ce,0, ThO, 
2.65 
(Di.La) 
5.22 
A C 
9.24 
MgO 
•07 
CaO Na,0 K,C 
.64 .20 .15 
.72 
Sp.Gr. 
4.201. 
Cacoclasite is the name sugges 
jnal white crystals present in 
>unty, Quebec. Dr. (ienth's ; 
ited by I 
a blue 
analyses \ 
calcilL- 
(Y.Er),03 MnO FeO 
