BILK \TI.S. TTTANATES, I.T< 



185 



l.uMer, vitreous; Trail-parent to t ranslueent ; n= 1.46; CO < 

 = .002 ; Optically () depending upon the amount of water. 



B.B. Intumesces and fuses easily to a blebby glass. Yields 

 water in the closed tube. Decomposes with HC1, yielding slimy 



silica. 



General description. Crystals are simple rhombohedrons, 

 nearly cubical in appearance, but the angle is 85 ; or combinations 

 of r and e with striations on both forms parallel to their intersec- 

 tions. Interpenetrating twins in which the vertical axis is the 



FIG. 504. Chabazite. Swan's Point, Nova Scotia. 



twinning axis are common. Upon the whole chabazite has very 

 much the appearance of fluorite, also granular or amorphous. 



Chemically the calcium and sodium content is variable, and they 

 replace each other, and at times barium, strontium, or iron may 

 enter the molecule. 



Chabazite in its occurrences is associated with the other zeolites 

 and under the same conditions. Good specimens are obtained at 

 Bergen Hill, New Jersey; at various points in Nova Scotia; as 

 well as at the noted zeolite localities of Europe, as the Giant's 

 Causeway, Faroe Islands, Iceland, and Aussig. 



ANALCITE 



Analcite. NaAl(SiO 3 ) 2 . H 2 O ; Isometric ; Type, Ditesseral Cen- 

 tral ; Common forms, n (211) other forms, as a (100) and d (110), 

 rare ; Cleavage, cubic in traces ; Brittle ; Fracture, subconchoidal ; 



