1894. | NEW YORK ACADEMY OF SCIENCES. 183 
wellite, from which latter it has wholly disappeared, as shown 
by the analyses quoted. The fresh biotite also shows much 
mugnesia and little or no lime, differing thus from the caswellite. 
These facts show that there is an unaltered manganesian bio- 
tite among the minerals found at the Trotter mine, which at least 
at one place has been altered by the loss of its alkalies, and pro- 
bably by other changes in its composition, so that it has practi- 
cally become a new mineral. This idea is strengthened by the 
fact that the mineral has been found only at one place in the 
mine. Though nothing is on record of its occurrence, its posi- 
tion and distribution in the dump shows that it was of local 
occurrence. It seems to indicate an influx at some point of 
water carrying with it manganese and calcium compounds, and 
perhaps helps to explain the finding of such a variety of min- 
erals at this most prolific locality. 
Inasmuch as these results seem to justify the view that it is a 
new mineral species, I propose for it the name Caswellite, after 
Mr. John H. Caswell, of New York, well-known among the min- 
eralogists of this vicinity. 
QUARTZ CRYSTALS FROM ELLENVILLE, N. Y. 
The quartz crystals which are the subjects of this commu- 
nication are from the mineral collection of Rutgers College. 
There is no record to show their exact source, but they 
came from the lead mine at Ellenville, Ulster county, N. Y., 
ENG. a) Pipe. 2) 
and have evidently been in the College collection for a long 
time. The first specimen is noticeable on account of the 
peculiar prolongation of its pyramid faces as shown in the ac- 
companying figures, which represent the crystal as it would ap- 
pear if what was evidently attempted had been completely carried 
out. In the actual specimen the projection is found on but five 
