1894. | NEW YORK ACADEMY OF SCIENCES. 181 
primexva, Heer; Magnolia alternans, Heer; Platanus Newberri- 
ana, Heer. 
As to the origin of these sandstones, which are not concre- 
tionary in their structure, or as to their probable connection 
with the clay outcrop in question, it would be useless to specu- 
late until the matter has been further investigated, and other 
portions of the shore searched for new material. 
The Section of Geology and Mineralogy then organized. The 
following papers were presented : 
ON CASWELLITE, AN ALTERED BIOTITE FROM 
FRANKLIN FURNACE, N.J.* QUARTZ CRYS- 
TALS FROM ELLENVILLE, N. Y. 
By Apert H. CHESTER. 
The mineral now under consideration is the one alluded to by 
the author at the meeting of the Academy, held October 30, 
1893.4 At that time a short account of its discovery was given, 
as well as a statement from Mr. F. L. Nason, as to its occur- 
rence and associations. Since then it has been examined at the 
laboratory of the New Jersey State Geological Survey, with the 
results given below. 
The new mineral is of a peculiar flesh, or light copper-red 
color, with a bronzy lustre and micaceous structure, closely re- 
sembling light-colored clintonite, for which it was at first mis- 
taken. Its hardness is 2.5—3, and its specific gravity is 3.54. It 
is completely decomposed by hydrochloric acid, with the separa- 
tion of gelatinous silica. It has entirely lost the elasticity of the 
original biotite and is quite brittle, so that while it still cleaves 
easily it has not the eminent cleavage of mica. It occurs in 
most intimate association with massive yellow garnet (polyadel- 
phite), granular rhodonite and a somewhat altered dark brown 
biotite, with which last it is most closely connected, in many 
instances the same plate of mica showing a gradual change from 
nearly black biotite at one end to caswellite at the other. It 
therefore is found in all stages of alteration, and varying in 
color from almost black to the bronze-red or pink described 
above. 
* By permission of Prof. John C. Smock, State Geologist of New Jersey. 
+ Trans. N. Y. Acad. Sci. xiii. 97. 
