Localities of Minerals. 243 
Gypsum—Cayuga Lake. We are informed by Dr. L. Foot, 
that the workmen who have excavated about 20 feet on the 
border of the lake, in gypsum, which is generally of a dark 
brown, or black colour, when they come to a transparent crys- 
tallized piece, call it isinglass, and reject it as worthless : the 
hint should be remembered by mineralogists, that the speci- 
mens may be saved for their cabinents. 
ASBESTOS IN ANTHRACITE. 
Extract of a letter from Dr. I. W. Webster. 
Boston, 27th Nov. 1818. 
Dear Sir, 
Iv examining some masses of the anthracite from Rhode 
Island, one piece attracted my attention, from the waved 
“ttucture of the lamelle into which it separated. The frag- 
ments of this were wedge-shaped, and I found the space be- 
tween some of the lamine filled up by a fibrous, silky sub- 
“lance, which induced me to break up other masses, in one of 
which I discovered an abundance of amianthus; the filaments 
ate of a light-green color in some parts of the mass-—in 
others presenting different shades of brown. With a micro- 
Scope, I found the fibres intermixed with the anthracite ; or 
forming thin layers, and these sometimes parallel to, at others 
“rossing, in different directions, the course of the lamine. 
How far the presence of this mineral may influence the igni- 
tion or combustion of the coal, is a question, perhaps, worth de- 
ining. Should my engagements permit, I shall make fur- 
ther €Xamination, and inform you. In the mean time, the no- 
tice of this fact may call the attention of some of your readers 
'0 the Subject. At any rate, this substance has, I believe, 
"ever before been noticed in connexion with anthracite, and 
* highly interesting in a geological point of view. 
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