390 



DESCRIPTIVE MINERALOGT. 



exposure to the atmosphere. The hepatic variety is mentioned by Cleaveland as having been 



found in this county. 



St. Lawrence County. There are several locahties in this county, where iron pyrites 



occurs both massive and crystalhzed. In the vicinity of Canton, there are extensive beds 



which may be advantageously employed in the manufacture of copperas. 



The hepatic variety of this mineral has been found in the vicinity of Pope's mill, associated 



with crystallized mica. It has a bronze-yellow colour, which tarnishes by exposure ; has a 



lamellar structure, and the laminae are easily separable. It is not magnetic. In its chemical 



characters, it agrees with the other varieties. 



The crystallized mineral is often associated with galena, numerous veins of which are known 



to occur in various parts of this county. The most interesting specimens have heretofore been 

 found at the Rossie vein. The colours are bronze and pinchbeck- 

 yellow, sometimes yellowish white. The lustre and finish of the 

 crystals are frequently very high, and their perfection does not appear 

 to be impaired by exposure. Among the forms which have been no- 

 ticed here, are the cube (Fig. 448) ; the cube with the edges replaced 

 by tangent planes, sometimes so slightly as to be scarcely perceptible, 

 Fig. 455 ; the cube with the angles and edges all replaced by planes, as 

 in Figs. 454, 456, 457 and 458 ; together with the triglyphe of Haiiy, 



Fig. 455. 



^-.-.. 



Fig. 456. 



Fig. 457. 



Fig. 458. 



Fig. 459. 



Fig. 459, in which the threefold cleavage is distinctly indicated by the stris. P on o 144° 44' 8"; 



on o' or &' 146° 26' 33" ; P on / or/' 143° 18' 2" ; V on d 152° 15' 52" ; d on/ 157° 



47' 33" [Haiiy). 



Fig. 460. Schoharie Cotinty. About a mile west of Schoharie court-house, 



iron pyrites occurs in great abundance in single crystals and groups, 

 in a decomposed clayey green shale. The colour is from brass 

 yellow to reddish brown. Small but very perfect cubes are found 

 in a kind of dark-coloured cellular heavy spar. In the slate, the ' 

 crystals generally have the form of the dodecaedre of Haiiy (Fig. 

 450). They are sometimes from half to three-quarters of an inch in 

 diameter. The forms represented in Fig. 455, 458 and 459, and the 

 compound one, Fig. 460, also occur at this locahty. 



