Geology of Massachusetts. 51 
Mine of Carbonate of Fron and Zine, in Sterling. 
This is a bed, in mica slate, just like that at Worcester; and was 
extensively explored forty or fifty years ago, for the same purpose 
which led to the opening of that bed, viz. the discovery of gold and 
silver. ‘The carbonate is the most abundant ore, and lies scattered 
about the excavation, in considerable quantities; although the sulphu- 
ret is common, which is sometimes arsenical. A reddish, foliated sul- 
phuret of zinc also occurs here, in considerable quantity, and some 
sulphuret of lead. Whether this mine will be found worth exploring, 
it is difficult, in its present state, to determine. If it afford the car- 
bonate of iron in large quantities, it will certainly repay the effort. It 
lies about a mile and a half south east of the center of the town. 
Chromate of Iron. 
It ought to be recollected, that a small rounded mass of this ore, 
so valuable in the preparation of the paint called chrome yellow, was 
found, a few years since, in Cummington, by Dr. Porter. 
j Phosphate of Iron. 
The earthy variety of this ore has been found, in considerable 
quantity, at the mineral spring in Hopkinton. It forms a bed, one 
or two feet below the surface, and has been employed as a pigment. 
It is said to exist also near Plymouth. 
_ Sulphuret of fron or Iron Pyrites. 
This is the yellow ore, so frequently mistaken for gold. It occurs 
more or less in almost every rock; but is of no use, unless it exists 
in large quantities, and is of that variety which easily decomposes. In 
such a case, it may be converted into the sulphate of iron; that is, into 
copperas. ‘The ore is broken up, and exposed to the action of air and 
moisture, when the change takes place, and the lixivium is evapora- 
ted to obtain the copperas. In Massachusetts, one can hardly avoid 
meeting with iron pyrites, and in the western part of Worcester coun- 
ty, the traveller cannot but notice, that nearly all the rocks are coated 
over with iron rust. ‘This is the result of the decomposition I have 
spoken of. In Hubbardston, the sulphate is so abundant, that a manu- ~ 
factory of copperas has been established, and I believe success has 
thus far attended the enterprise. I should presume, that copperas 
might be manufactured in several other towns south of Hubbards- 
