284 DESCRIPTIONS OF MINERALS. 



Dark brown tourmalines are obtained at Orf ord, N. H. ; 

 in thin black crystals in mica at Grafton, N. H. ; Monroe, 

 Ot. : G-ouverneur and Amity, X. Y. ; Franklin and Newton, 

 1ST. J. A fine cinnamon-brown variety occurs at Kings- 

 bridge and Amity, Orange Co., X. Y. and also south in JSew 

 Jersey. A gray or bluish-gray and green variety occurs near 

 EclenVille. 



The word tourmaline is a corruption of the name used in 

 Ceylon, whence it was first brought to Europe. Ly murium 

 is supposed to be the ancient name for common tourmaline ; 

 and the red variety was probably called hyacinth. 



The red tourmalines, when transparent and free from 

 cracks, such as have been obtained at Paris, Me., are of great 

 value and afford gems of remarkable beauty. They have 

 all the richness of color and lustre belonging to the ruby, 

 though measuring an inch across. The yellow tourmaline, 

 from Ceylon is but little inferior to the real topaz, and is 

 often sold for that gem. The green specimens, when clear 

 and fine, are also valuable for gems. Plates from pellucid 

 crystals cut in the direction of a vertical plane are much 

 used for polariscopes. 



GeMenite. Tetragonal, like the scapolites, and grayish green in 

 color. G. =2 9-3-07. Formula Ca 3 A10 in Si o with some of the Al re- 

 placed by ^e, and some of the Ca by Fe and Mg. From Mount 

 Monzoni in the Fassa Valley. 



Andalusite. 



Trimetric. In rhombic prisms, which are nearly square ; 

 7a/=90 c 48'. Cleavage lateral; sometimes distinct. Also 

 massive and indistinctly coarse columnar, but never fine 

 fibrous. 



Colors gray and flesh-red. Lustre vitreous, or inclining to 

 pearl v. Translucent to opaque. Tough. H. =7*5. G-. = 



~ HQHO 



Composition. A10 3 Si = Silica 36-9, alumina 63*1 = 100. 

 B.B. infusible. Ignited after being moistened with cobalt 

 nitrate assumes a blue color. Insoluble in acids. 



