230 W. G. Mixter on Willemite and Tephroite. 
Art. XXI.—Contributions from the Sheffield Leiboreti 
Yale College. No. XVII.—On Willemite and Tephroite 
Witiram G. Mixter, Ph.B., Assistant in the 
Laboratory. 
Tue willemite occurring in the well known franklinitea 
zincite veins at Mine Hill and Stirling Hill in Sussex Co., Ne 
Jersey, has been frequently analyzed; but the results obtain 
by different chemists vary considerably.* This variati 
be explained in part by the fact that specimens taken in 
near the surface are sometimes a by the oxydation of > 
oi val le-green Willemite.—This variety is found in 
erable abundance on Mine Hill, but is apparently of not & 
quent occurrence at the Stirling Hill mines. It has a 
apple-green cclor, shading in some instances woe 
In most specimens it is intimatelymixed ed with fra 
ite and calcite, but the masses are often 8 
allow of its easy selection free from these nivel 
culty was experienced in obtaining the 
pure for analysis. Specific gra 
aes ‘5. A qualitative analysis indicated besides zine 
+ | 
Cnn oo 
ri | 
l| 
AS 
_ 
eis 
— 
© 
tot 
at 
Be 
° 
Boe 
_ tive separation of the iron was effected by precip 
basic-acetate, and from the filtrate the manganese 
down as oxyd a oxydation with bromine, this ee 
off, washed and re-dissolved and preci itated ws 
- soda and weighed as proto-sesquioxyd. 
: pat i ay the filtrate from the oxyd of manga 
_ subsequently re-dissolved and precipitated by car a 
The magnesia was separated if rom the filtrate from | 
* For analyses, see Dana's Mineralogy, bth ed., p. 26% 
