204 PHYSIOGRAPHY. 



Spinel Spodumene. 



The United States afford some very remarkable varieties of the pres- 

 ent species; the most distinguished of which is one of a black color in 

 crystals, varying from one to sixteen inches in circumference, which is 

 found at Amity, (N. Y.) These crystals exist in groups, often lining the 

 sides of partial veins with Calcareous Spar and Crichtonite in serpentine. 

 They are often in twin-crystals. The same neighborhood produces an 

 abundance of smaller crystals of various shades of green, black, red and 

 brown, and which are imbedded in granular limestone, usually associated 

 with Brucite, Hornblende and Pyroxene. The secondary forms above 

 quoted are found at Hamburg, (N. J.) where they are found in Cal- 

 careous Spar and Quartz, associated with Scapolite. They present rich 

 shades of green and blue, and frequently the crystals are transparent 

 Pearl-grey crystals, simple and compound are found at Newton, (N. 

 J.) in limestone accompanying the blue Corundum, Tourmaline and 

 Rutile. Black Spinel has been found at Munroe, (N. Y.) Green and 

 blue, and more rarely red varieties occur in Bolton, Boxborough and 

 Littleton, (Mass.) imbedded in white limestone. 



SPINELLANE. (See Sodalite.) 



SPODUMENE. Prismatoidal Disthene-Spar. 



Primary form. Oblique rhombic prism. M on M = 

 93. 



Cleavage, parallel to the shorter diagonal of the prism? 

 perfect also to bases crblique to the obtuse edge of the prism 

 and forming with it angles of 135 . . . 138, less perfect 

 than the former. In distinct cleavages also, apparently 

 forming tangent truncations of the acute solid angles. 

 Fracture uneven. 



Lustre pearly. Color various shades of greyish-green ; 

 passing into greenish-white. Streak white. Translucent. 



Brittle. Hardness = 6-5 ... 7-0. Sp. gr. = 3-170. 



Compound J^arieties. Massive : composition granular, 

 of various sizes of individuals, generally large. 



