HYDKOUS SILICATES — ZEOLITE SECTION. 301 



Silica 52*20, alumina 18*27, lime 6*58, soda and potash 2*12, 

 water 20 '52. B.B. intumesces and fuses to a nearly opaque 

 bead. Decomposed by hydrochloric acid, with the separa- 

 tion of slimy silica. In the closed tube gives water. Phac- 

 olite is a variety in complex glassy crystals. 



Dijf. The nearly cubical form often presented by the 

 crystals of chabazite is a striking character. It is distin- 

 guished from analcite as stated under that species ; from 

 calcite by its hardness and action with acids ; from fluorite 

 by its form and cleavage, and its showing no phosphores- 

 cence. 



Obs. Found in trap and occasionally in gneiss, syenyte, 

 and other rocks. Chabazite is met with in the trap of Con- 

 necticut Valley, but in poor specimens ; also at Hadlyme 

 and Stonington, Conn.; Charlestown, Mass.; Bergen Hill, 

 X. J.; Piermont, X. Y.; Jones's Falls, near Baltimore 

 (Haydenite). Nova Scotia affords common chabazite, and 

 also the acadialite in abundance. The Faroe Islands, Ice- 

 land, and Giant's Causeway, are some of the foreign locali- 

 ties ; also the County of Antrim, Ireland. 



Herschelite. Near chabazite, if not identical with it. From Sicily. 



Gmelinite. Closely resembles some chabazite, but its crystals are 

 usually hexagonal rather than rhombohedral in appearance. Formula 

 (Xa 2 ,Ca)Al 2 0,nSi4. A Bergen Hill specimen afforded Silica 48 67, alu- 

 mina 1872, lime 2-60, soda 9'14, water 21-35=100-48. Gelatinizes with 

 hydrochloric acid, but in other respects resembles chabazite. Occurs 

 at Andreasberg ; in Antrim, Ireland ; in Skye ; at Bergen Hill, N. J. ; 

 in Xova Scotia at Cape Blomidon. Named after the chemist, Gmelin. 



Levynite (Levyne). Rhombohedral, and somewhat resembling gme- 

 linite in its crystals ; excluding the water, having the quantivalent 

 ratio of labradorite, 1:3:6. Colorless, white, grayish, reddish. From 

 Iceland, Greenland, Antrim, Londonderry, Hartfield Moss near Glas- 

 gow. Named after the crystallographer, Levy. 



Harmotome. 



Aionoclinic. Unknown except in compound crystals; and 

 commonly in forms similar to the annexed figure ; also in 

 compound rhombic prisms. 



Color white ; sometimes gray, yellow, red, or brownish. 

 Sub transparent to translucent. Lustre vitreous. H. = 4'5. 

 C—2-45. 



Composition. BaAl O u Si 5 4- 5 aq = Silica 46 *5, alumina 1 5 *9, 

 baryta 23*7, water 13 -9 = 100 ; but a little of the baryta re- 

 placed by potash. B.B. whitens, crumbles, and fuses quietly 



