Geology and Mineralogy of a part of Massachusetts, &c. 59 
specimens, the quantity of serpentine is very small, and 
the colour yellowish white. In other specimens the ser- 
pentine is distinctly to be seen. ‘The mineral effervesces 
with acids, and the crystalline structure of the limestone or 
of the magnesian limestone, is obvious. I have supposed 
ita magnesite; but its characters would place it under the 
general description of Vert Antique. 
Cummingtonite. 
I have given this name to a mineral found by Dr. J. Por- 
ter in Cummington. It appears to be a variety of epidote. 
Its colour is gray, sometimes with a faint reddish tinge, un- 
less when acted on by the weather, when its colour is yel- 
lowish. It is in indistinct prisms, with oblique seams like 
zoisite, and in radiated or fascicled masses, which are com- 
posed of slender prisms. Lustre somewhat shining or 
pearly. It is nearly as hard as quartz, and sometimes 
makes a slight impression upon rock crystal. Before the 
blowpipe it blackens, and a small portion melts, when the 
heat is very great, into a black slag, which is attracted by 
the magnet. Its point of fusion seems to be about the same 
as that of zoisite. After allowing for some absorption, the 
sp. gr. may be taken as about 3.42. It is so peculiar a 
mineral, that it deserves, even as a varicty, a particular 
name. 
With quartz and garnet, it forms a large mass in Cum- 
mington. The cavities in the rock contain pulverulent 
sulphur of a dirty greenish colour; and minute crystals of 
magnetic oxide of iron are also found in it. 
Vente. 
This mineral is found at Chatham, Con. It is foliated in 
its structure, but less distinctly lamellar than specimens 
which I have seen from Europe. It is dark green, opaque, 
hard as yenite, and easily fusible into a dull black globule. 
From a partial analysis, it seems to have the composition 
of t he European yenite, and the silex and iron are nearly 
in the proportions given by analysis. Sp. gr. 3.83. When 
melted, the globule is like that of the European yenite, at- 
tracted by the magnet. It is also in the form of flattened 
