PHYSIOGRAPHY. 



Laumonite La zulite. 



The faces parallel to the principal axis striated in that di- 

 rection. 



Lustre vitreous, inclining to pearly upon the more dis- 

 tinct faces of cleavage. Color white, passing into reddish, 

 yellowish, or greyish tints. Streak white. Translucent. 



Not very brittle. Hardness = l*5 . . . 5*5. Sp. gr.=2*3. 



Compound Varieties. Massive : composition granular, 

 commonly elongated in one direction, faces of composition 

 generally streaked. 



1. Before the blow-pipe, it melts into a white spumous mass. It ge- 

 latinizes with acids, and acquires negative electricity by friction, if iso- 

 lated. It is decomposed by the action of the atmosphere, and loses its 

 water; it is therefore generally met with in a friable state, and most of 

 its properties are on that account but imperfectly known. 

 2. Analysis. 



Silica - - 4830 - - - 49-00 



Alumina - - 22-70 - - - 22-00 



Lime - - 12-10 - - - 9-00 



Water - - 16-00 - - - 17-50 



Carbonic acid - - 0-00 - - - 2-50 



3. It occurs in veins, traversing clay-slate with limestone : also in ir- 

 regular veins and imbedded masses in porphyry, and in the cavities of 

 amygdaloidal rocks. 



4. The original locality is in the lead mines of Huelgoet in Brittany, 

 It was next found near Schemnitz in Hungary, in porphyry. It occurs 

 likewise on Mount St. Gothard with Apatite, in Faroe, Iceland, and va- 

 rious parts of Scotland, Ireland, and in Nova-Scotia. 



In the United States it has been met with occasionally, in small masses, 

 in the amygdaloid of Connecticut and Massachusetts ; and at Phillips- 

 town, (N.Y.) 



LAZULITE. Prismatic Azure-Spar. MOHS. 



Primary form. Right rhombic prism, M on M=I31 Q 

 30'. 



