210 PHYSIOGRAPHY. 



Stilbite. 



strongly cohering. Massive : composition imperfectly co- 

 lumnar, individuals broad 5 straight, and radiating from com- 

 mon centres strongly coherent. Often these compositions 

 are again aggregated iuto granular masses. "Globular shapes 

 formed in vasicular cavities. 



1. Before the blow-pipe, it yields an opake vesicular globule. It does 

 not gelatinize with acids. 



2. Analysis. 

 By HISINGER. 



Alumina 16-10 



Silica . . . . . . . 58-00 



Lime . . . - v 9 ' 20 



Water . . . . * . ' . . . 16-40 



3. Its principal repositories are, the vesicular cavities of amygdaloidal 

 rocks, and certain metalliferous veins. It is also found lining seams in 

 gneiss. The accompanying minerals are Heulandite and Chabasie, and 

 when in metallic veins, it is generally attended by ores of silver, lead, 

 copper and iron. 



4. Magnificent crystals of a white color are met with in the vesicular 

 cavities of the amygdaloids of Iceland and the Faroe Islands. Similar va- 

 rieties have been brought alsofrom Indore in the Vendyah mountains in 

 the East Indies. Those from the Tyrol are mostly compound and of a 

 brick-red color. Beautiful crystals of this color occur near Campsie in 

 Stirlingshire, though the present species is less common in Scotland 

 and the Western Isles, than that of Heulandite. The crystals from the 

 silver veins of Andreasberg in the Hartz are generally small, so are also 

 those which occur in the iron mines of Arendal and in the beds of cop- 

 per-ore in the Bannat of Temeswar. Handsome varieties of a white col- 

 or occur in the Basin of Mines, Nova Scotia, in trap, attended with other 

 species of this family. 



But few localities of Stilbite are known in the United States; and 

 these generally unimportant. The most interesting is that at Hadlyme, 

 (Conn.) where it lines the walls of seams in gneiss in stellular concre- 

 tions of considerable dimensions, associated with Chabasie, Heulandite 

 and Epidote. Under similar circumstances, it occurs at West Farms, 

 (N. Y.) and Bellows falls, (Vt.) It has been met with at Saybrook in 

 gneiss in small reddish crystals associated with Molybdenite. Also in 

 small quantity, in vesicular cavities of greenstone trap at various 

 places in Connecticut and Massachusetts. 



