PHYSIOGRAPHY. 259 



Heulandite. 



Lustre vitreous. The faces P possess high degrees of 

 pearly lustre, both as faces of cleavage and of crystalliza- 

 tion. Color, various shades of white, prevalent, passing 

 into red, grey, and brown. Streak white. Transparent 

 . . . translucent on the edges. 



Brittle. Hardness = 3-5 ... 4-0. Sp. gr. = 2-200. 

 White crystals from Iceland. 



Compound Varieties. Massive : composition granular, 

 the individuals being of various sizes, sometimes easily sep- 

 arable, sometimes strongly cohering ; faces of composition 

 uneven and rough. Globules formed in vesicular cavities. 



1. Before the blow-pipe, it melts with a slight intumescence, during 

 which it emits a phosphoric light. 



2. Analysis. 



By LAUGIER. By WALMSTEDT. 



fr. the Tyrol. 

 Alumina . . 10-00 . . . 7-99 



Silica . . 45-00 . . . 59-90 



Carbonate of lime . 16-00 . . . 0-00 

 Lime . . 11-00 . . . 16-87 



Water ;. . 12-00 . . . 13-43 



Oxide of iron . . 4-00 . . . 0-00 

 Oxide of manganese . 0-50 . . . 0-00 



3. The varieties of Heulandite are usually found accompanied by Stil- 

 bite, in the vesicular cavities of amygdaloidal rocks, and in certain metal- 

 liferous veins. 



4. Iceland and the Faroe islands afford the most magnificent crystals of 

 Heulandite, of a pearly white color, and often transparent. A similar 

 variety comes from the Vendyah mountains in Hindostan. The brick- 

 red crystals and compound masses occur in the Tyrol and in Scotland. 



In North America, the present species is found in great perfection in 

 large white crystals, at Cape Blomidon in Nova Scotia. It has also been 

 met with along with Chabasie upon mica slate, at Chester, (Mass.) and 

 with Stilbite and Chabasie on gneiss, at Hadlyme, (Conn.) 



HlSlNGERITE. 



Massive. Cleavage distinct in only one direction. Fracture 

 earthy. 



