504 Scientific Geology. 



This mineral occurs also in Sterling in a granite rock. This 

 spodumene has more of a pearly aspect than that in the western part 

 of the State ; as the specimens in the collection will show. It is also 

 of a more milky white color. (No. 1508) 



Dr. Emmons is of opinion that " the large cleaveable variety" of 

 lepidolite occurs in Goshen. Probably he refers to the mineral that 

 has been generally regarded as rose mica. 



The varieties of mica in our granite are numerous and interesting. 

 The rose red just referred to, has been found only I believe in the 

 northwest part of Goshen, where it sometimes occurs in oblique 

 rhombic prisms ; which is its primary form. In the same place, also, 

 and likewise in the northwest part of Chesterfield, at the tourmaline 

 locality, a delicate yellow mica of various shades is found under the 

 same form: and still more frequently, a transparent or silver col- 

 ored variety. But the most remarkable locality of crystalized 

 mica is in Ackworth New Hampshire: where are found finer speci- 

 mens, associated with beryls and rose quartz, than at any "other spot 

 in this country. The crystals are distinct six sided tables,disseminat- 

 ed through gray quartz, and attached to fine grained feldspar. They 

 vary in size from half an inch in diameter to an inch and a half. I have 

 some reason to fear, however, that this locality may not prove very 

 prolific. 



Prismatic mica is found in Goshen, Chesterfield, Norwich, and 

 Leverett. But the specimens which I found in Russell are the best. 

 (Nos. 1 5 12 to 1514) The general color of the prisms is light smoke 

 gray : but we sometimes see in them distinct strips, penetrating deep 

 into the specimen, of a very dark bronze color ; appearing black in- 

 deed, except in very thin plates. 



Plumose mica (Mica fibreux, Beudant,) is quite common in Wil- 

 liamsburg, in several places west and north vvest of the village. The 

 name is derived from the resemblance between the arrangement of its 

 lamellae and those of a feather: which indeed is often quite striking. 

 ,JThe granite of Massachusetts contains almost every variety of the 

 schorl family that has been found on the globe. Common black schorl 

 is most abundant. In Chesterfield and Goshen its crystals are some- 

 times large, but generally quite imperfect. In Norwich its crystals 

 are terminated by pyramids. In Westford, also, I met with it in small 

 very short acuminated crystals. (No. 1547) 



Of the tourmalines we have every variety, except perhaps the yel- 

 low and the white. Indicolite occurs at the greatest number of lo- 



