346 



Scientific Geology. 



with prisms of this mineral, of the size of a goose quill, and generally 

 acuminated. The specimen was weathered so as to leave the schorl 

 in bold relief. 



Scapolite is found at Chester, as already mentioned ; and Dr. Em- 

 mons in his Mineralogy says that it exists " in veins in mica slate, asso- 

 ciated with hornblende, pyroxene, and garnet ; but the crystalization is 

 generally confused and indistinct." It is unnecesary to refer again to 

 other localities of hornblende and pyroxene as connected with mica 

 slate ; except to say, that Dr. Emmons mentions " Middlefield, Ches- 

 ter, Hinsdale, and most of the mountain towns in New England," as 

 containing sahlite and coccolite. 



Garnet is more widely disseminated in mica slate than any other min- 

 eral. It differs in size from an almost microscopic grain, to a crystal of 

 two inches in diameter ; and its colours are generally reddish, but some- 

 times black, even approaching very nearly to melanite. In the slate con- 

 taining the sappare at Chesterfield, the reddish garnets are very numer- 

 ous and sometimes quite large. In the amphibolic aggregates, the gar- 

 nets are usually black. In Plainfield, Dr. Porter has found garnets dis- 

 seminated in quartz. Garnet and staurotide are usually associated ; as 

 at Chesterfield, Middlefield, and Chester. The usual form of the crystal 

 is a rhombic dodecahedron, which is sometimes truncated on its edges. 



The mica slate formation in Williamsburg, Middlefield, Chester, 

 Hinsdale, Cummington, Worthington, Plainfield, &c, frequently 

 contains crystals of epidote. Generally they are imbedded in quartz, 

 and frequently associated with hornblende and augite. Zoisite, now 

 regarded by able mineralogists as a species distinct from epidote, oc- 

 curs also in Goshen, Hawley, Middlefield, Chester, Hinsdale, Ches- 

 terfield, Conway, Windsor, and particularly in the north part of Ley- 

 den, in large quantities. Indeed, it may be found scattered over .near- 

 ly every part of the Hoosac Mountain range of mica slate; and on 

 the same range as far northward into Vermont as I have examined. 



In the stone walls fifty rods west of the residence of Gov. Lincoln 

 in Worcester, several specimens of Idocrase were found a few years 

 ago, associated with massive garnet and pyroxene. It was crystal- 

 ized in right rectangular prisms, truncated on the lateral edges so as 

 to produce eight-sided prisms. There can be little doubt that the rock 

 containing this mineral, belonged originally to the mica slate range 

 of Worcester valley. It appears from Beudant's work on mineral- 

 ogy, that it exists in mica slate in Europe, although generally of vol- 

 canic origin. As the Worcester locality is now exhausted,'! am in- 



o 



