GLUCINA. 



375 



Geological Situation. This mineral, when in crystals, has heretofore been found in veins 

 traversing granite. It also occurs in fractured crystals and rolled masses in secondary depo- 

 sits. The most splendid crystals of emerald are found in a vein of magnesian limestone, 

 which traverses a hornblende rock at Muso, near Santa Fe de Bogota, in Grenada. 



LOCALITIES. 



New- York County. Beryl is said to have been found near New- York, in small, pale 

 green, semi-transparent crystals, in granite ; and also in a similar deposit near Sing-Sing in 

 Westchester county.* 



This mineral is as yet quite rare in this State, which is somewhat remarkable, as it is ex- 

 ceedingly abundant throughout New-England, especially in Massachusetts and Connecticut. 

 At Acworth in New-Hampshire, crystals have been found weighing from two to three hundred 

 pounds, and measuring four feet in length. 



CHRYSOBERYL. 



[From the Greek XP""'"?) gold, and /SrjpuXXos, heryl ; because it is a superior kind of beryl.] 



Cymophane. flafly and Beudant. — Chrysoberyl. Cleaveland, PhiUips, Thmmon, Shepard and Dana. — Pris- 

 matic Corundum. Jameson. — Prismatischer Korund. Mohs. 



Description. Colour asparagus-green passing into greenish white, 

 olive green and yellowish grey ; it often exhibits a milk-white opale- 

 scence. Streak white. It occurs regularly crystallized, and in rolled 

 fragments. The primary form is a right rectangular prism. Fig. 398. 

 Cleavage parallel to the plane M, and with difficulty also parallel to 

 the plane T, and to the longer diagonal of the prism. Fracture con- 

 choidal. Lustre splendent and resino-vitreous. Transparent to trans- 

 lucent. Hardness 8.5. Specific gravity from 3.65 to 3.80. Infusi- 

 ble before the blowpipe alone ; with borax, it fuses with difficulty into a transparent glass. It 

 becomes electric by friction. 



Composition. Silica 4.00, alumina 73.60, glucina 15.80, oxide of titanium 1.00, pro- 

 toxide of iron 3.38, water 0.40 (Seybert). 



Geological Situation. When in place, chrysoberyl is usually imbedded in granitic veins, 

 and is associated with various other minerals peculiar to the primary rocks. 



locality. 



Saratoga County. The only locality of chrysoberyl at present known in this State, is in 

 the town of Greenfield, about a mile north of the village of Saratoga-Springs. It occurs in a 



Pierce, Torrey and Maclure. Clemeland'a Mineralogy. 



