220 



DESCRIPTIVE MINERALOGY. 



V 



■ ™- At Brownvillc, four miles from Watertown, perfect crystals 



have been found in the form of the equiaxe of Haiiy (Fig. 58) ; 

 and the same with the edges rounded, forming lenticular crys- 

 tals (Fig. 70). 



There remains still to be noticed a locality in the town of 

 Wilna, about a mile northeast of Natural bridge. Crystals of 

 calcareous spar are found in seams in the primary limestone. 

 They are white, and exhibit a variety of forms, as the low 

 six-sided prism, elongated dodecahedrons, and rhombohedrons 

 with various truncation. They are, however, seldom sufficiently perfect for accurate mea- 

 surement. In the same vicinity, there are large masses of this mineral so loosely aggregated 

 that a blow of a hammer causes them to separate into rhombohedrons of various sizes. The 

 smaller specimens are translucent, and have a delicate and beautiful blue tint. This colour is 

 probably owing to oxide of iron ; but if so, the quantity is too small to be easily detected by 

 analysis. 



Lewis County. This county abounds in localities of calcareous spar, 

 which aiford a variety of interesting forms. It occurs in the Trenton 

 limestone, and is often associated with galena, iron pyrites and fluor spar. 

 The most common form is the dodecaedre of Haiiy (Fig. 62), which 

 occurs at Leyden, Lowville and Martinsburgh. The prism, however, 

 is often much compressed, as in the accompanying Fig. 71. At Low- 

 ville, the calcareous spar is associated with iron pyrites and cubical 

 crystals of fiuor spar, in a vein on the banks of the creek near the falls. 

 At Martinsburgh, the best crystals were obtained from the excavations that were made for 

 lead ore, with wliich they are here often associated. In addition to the lenticular crystals 

 which occur at this locality, are several modifications of the dodecaedre, some of which are 

 represented in Figs. 72, 73, 74 and 75 : 



Fig. 72. 



Fig. 73. 



Fig. 74. 



Fig. 75. 



