Minerals in Mica Slate. 



345 



with which I am acquainted respecting these beds ; except that I have 

 since ascertained that nearly all of the manganese ore is the ferro-sil- 

 icate, or Fowlerite. (No. 1027.) 



The best locality of fibrolite that has been discovered in this slate, 

 is in Lancaster, near the village. It is found in a bowlder. 

 The fibrous structure is sometimes almost changed into the fo- 

 liated. The masses are from an inch to three or four inches long, 

 and half an inch broad. It has been met with, also, in some other 

 places in the State. 



The localities of sappare are numerous. The best is Chesterfield ; 

 from whence large quantities have been obtained; some of it finely 

 crystalized and of a rich colour. Its colours vary from nearly white, 

 to dark blue. It is not possible at present to obtain specimens as fine 

 as No. 750. It is found also in Blanford, Worthington, Middlefield, 

 Deerfield, &c. The Rhoetizite is found in Blanford and Russell, ac- 

 cording to Dr. Emmons. In Canton Ct. this mineral occurs crystal- 

 ized and of a green colour. 



Of the situation of staurotide in Massachusetts, I have given a gen- 

 eral account in describing the staurotidiferous mica slate. Chester- 

 field perhaps, near the locality of green and red tourmalines, is as good 

 a spot for procuring specimens as any one in Massachusetts. But no 

 specimens found in this State equal those from the western part of 

 New Hampshire. 



Dr. Emmons states in his Mineralogy, that pinite is found in Ches- 

 ter : though he does not mention the rock in which it occurs. I 

 mention it here merely because mica slate is the predominant rock 

 in Chester. 



_ If andalusite and made are the same species, then the most abund- 

 ant locality in Massachusetts is in Lancaster, in clay slate. But the 

 mineral which has been generally called andalusite, is most abundant 

 in Westford, in mica slate. And I am happy to state that numerous 

 specimens can be obtained from thence. It occurs in the stone walls, 

 from a hundred rods to a mile east of the center of the village, and 

 may sometimes be found in distinct prisms, greatly resembling spec- 

 imens from Germany. It is of a reddish colour, and sometimes the 

 masses are 2 or 3 inches across. Generally they are accompanied 

 by a fibrous mineral, resmbling talc : but I am not satisfied as to its 

 nature. 



Schorl is not common in mica slate. But in Norwich I found a 

 curved specimen of this rock, nearly a foot square, entirely covered 

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