Mineralogy, Geology, &c. 37 
are somewhat higher. Here the water glides down pretty 
rapidly over a bed of solid limestone. From the appear- 
ance at this place, and from various other reasons which J 
have not now time to state, I have no doubt but at some 
ancient period of time this northern extremity of Lake Erie 
was entire, and the waters of this and the upper lakes emp- 
tied themselves through a southern channel. 
3. New Locality of Chrysoberyl. 
Saratoga Springs, July 29, 18 21. 
TO PROFESSOR SILLIMAN. 
Dear Sir, 
I hasten to inform you of the discovery of a new locality 
of Chrysoberyl and Prismatic Mica, presuming that, as these 
minerals have not occurred very frequently in the U. States, 
it may afford you some gratification. ‘They are found in a vein 
of granite which passes through gneiss; the vein was dis- 
covered some years ago, and fine specimens of laminated 
mica and common schorl, (black tourmaline) which occur 
im great abundance, and sometimes in beautiful, (though 
not perfect,) crystals, were taken from it. The rock in 
which this vein is'situated, is about one mile north from the 
high-rock springs at Saratoga, and forms a part of the prim- 
itive region which approaches us from the north, and ter- 
minates, or passes beneath the secondary, near this spot. 
The surface of this rock is somewhat elevated, and remains 
uncovered for the distance of from two to three hundred ° 
yards ; the vein is observed to traverse its whole extent. 
The minerals which are found in this vein, are 
Ist. Felspar,—this assumes more or less the crystaline 
form, and affords well defined crystals of adularia. 
2d. Common schorl—this is in great abundance ; it is 
mostly in amorphous masses, from the size of an egg down 
to that of the smallest pin’s head, it however, sometimes 
possesses a more regular form, presenting from two to five, 
or more sides of a beautiful crystal, with a one or two sided 
termination, while the remainder is irregularly diffused in 
the mass of its gangue. The colour is a shining velvet 
black. Itis perfectly opaque. 
