SCIENTIFIC SURVEY. 411 



grass green, are very abundant at this place, and though not often 

 found in perfect crystals, are usually bright and nearly transparent. 

 They are generally imbedded in mica or quartz, and frequently 

 have a radiated structure consisting of thin, flat, or needle like 

 crystals, diverging from a common centre. Sometimes crystals 

 are green externally and red within, or the reverse, and sometimes 

 one end is green while the other is red or blue. The red varieties 

 are the most rare, and perhaps the most interesting. They occur 

 of various shades, from pale pink to ruby red and deep crimson, 

 and are generally transparent, and occasionally, are found in 

 perfect crystals, when they are very beautiful. This variety has 

 been called Rubelliie from its color. In addition to these colors, 

 pure white specimens are not uncommon, as well as various shades 

 of brown, but these are not usually considered of much interest 

 by collectors. 



Beryl. Associated with the large crystals of black tourmaline 

 and sometimes imbedded in them, very good specimens of beryl 

 are sometimes met with. These are hexagonal prisms, generally 

 somewhat irregular in form, and not often with the ends perfect, of 

 a light green color, translucent, and vitreous in lustre. The hard- 

 ness is greater than that of quartz. 



Mica. Large quantities of this mineral, from which the locality 

 has taken its name, may always be obtained. It occurs in imper- 

 fectly crystalized masses or sheets, often a foot or more in diam- 

 eter, but seldom of suiEcient purity or transparency to be of com- 

 mercial value like that from Acworth and Grafton, N. H., which 

 is used for the doors of stoves, lanterns, etc., and of late, to a 

 considerable extent, for delicate photographic plates. The name 

 Muscovile is also applied to this mineral. 



Feldspar. The principal part of the vein in which all the min- 

 erals previously mentioned are found, consists of a grayish variety 

 of feldspar, occurring in imperfectly crystalized masses, of but 

 little interest or value, unless it be regarded in connection with the 

 origin and nature of the vein and the relations of the different min- 

 erals, one to another, which are questions that cannot, with pro- 

 priety, be discussed here. 



AlMle. The variety of albite which has been called by some 

 mineralogists, Gleavelandite, occurs quite abundantly at Mt. Mica. 

 It is generally in the form of masses consisting of flat flakes of 

 about an inch in diameter, united together in various ways, and 



