105 
these Shales have usually been assumed to consist, and 
correspond to Mica, (Muscovite) 2°80, with a small increase 
due to the Limonite present. On close examination, accord- 
ingly these Shales are found to be composed essentially of 
disintegrated Mica. It may be added that different layers of 
the Trapoid Schists that underlie the Palisades, and which 
appear to have been left in a sort of transition state of 
incipient conversion, from the sedimentary beds into Crystal- 
line trap, gave densities from 2°63, (that of the compact part 
of the ‘‘Sandstones,” or of a Feldspar) to 2°80, (that of the 
compact Shales or of a Mica.) 
November 21, 1870. 
The President in the chair. ‘Twenty persons present. 
The President announced that the Lecture Committee would 
consist of Messrs. Squier, D. 8. Martin, Brevoort, Newberry 
and Brownne. 
Dr. L. FEUCHTWANGER exhibited a fine specimen of 
Greenockite, Sulphuret of Cadmium, reported to come from 
Friedensville, Penn. If so, this is a new locality for this 
mineral. He also called attention to what he‘said was a 
New American Locality for Cobalt and Nickel; illustrating his 
remarks by specimens. The recent discovery, and the suc- 
cessful working of a’mine of very rich native Silver and 
Argentiferous Galena in Lake Superior, had caused consider- 
able stir among mineralogists as well as among those 
commercially interested in the metallurgic resources of our 
country. The locality was a small Island in Lake Superior, 
at the mouth of Thunder Bay and just off of Thunder Cape. 
During last year it was reported that eight tons of Ore has 
been gotten out, which had yielded a return of five thousand 
dollars; subsequently ten tons had yielded fully three 
thousand dollars. The specimens exhibited, coming from 
