EXTRA-UMITAL SPECIES. 453 



NITRE. 



rvitrato of Potasli. Clmvcliinil. 



Colour wliitc. In cn]>illary crystals and crusts. Transparent to semi-transparent. ITanl- 

 ness 2.0. Sp.gr. 1.94. Dissolves in water. Composed of Jiilratc of potaslj, and several 

 salts of lime, in variable jiroportions. 



With nitrate of lime and other sails, in the salt-pelre caves of Kentucky, ice. 



PETALITE. 



Colour white or reddish white. In lamellar masses. Lustre glistening. Translucent. 

 Hardness G.O. Sp. gr. 2.41. Before the blowpipe, it melts only on the edges. Composed 

 of silica 79.21, alumina 17.22, litliia.5.7G. 



Bolton, Massachusetts. 



FINITE. 



Colour grey, greyish green or brown. Crystallized. Primary a liexagonal prism. Lustre 

 sometimes resinous. Opaque. Hardness 2.0 to 2.50. 8p. gr. 2.75 to 2.78. Whitens 

 before the blowpipe, and fuses on ihin edges, but docs not melt. Composed of silica 55.90, 

 alumina 25.48, potash 7.89, soda 0.. 39, peroxide of iron 5.51, magnesia with manganese 

 3.76, water 1.41. 



Lancaster in Massachusetts, and Haddam in Connecticut. It has been ihouLdit to be a 

 variety of mica. 



POLYMIGNITE. 



Colour black. In prismatic crystals. Primary a rhoraVioidal octahedron, the dihedral 

 angles of which arc 136° 28', 116° 22' and 80° 16'. Lustre imperfect metallic, but brilliant. 

 Hardness 0.5. Sp. gr. 4.77 to 4.85. Infusible before the blowpipe. Composed of oxide 

 of titanium, zirconia, yltria, oxide of iron, etc. 



Beverly, Massachusetts (ShrjianJ). 



PURPLE COPPER. 



Varicgati'd Pyritous C'-oppcr. Clrmvliind. 



Colour lictween copper-red and lomliac-brown. Streak pale greyish black and sliining. 

 Crystallized and massive. Primary a regular octahedron. Lustre metallic. Rather scctile. 

 Hardness 3.0. Sp. gr. 5.00. Melts before the blowpipe. Composed of copper 61.07, 

 sulphur 23.75, iron 14.00, sihca 0.50. 



Chesterfield, MassachuiClts ; i'erkiomcn, Pennsylvania. 



