PHYSIOGRAPHY. 279 



lodic Silver. 



Hardness = 5-5 ... 6-0. Sp. gr. = 2-72. 

 1. It is infusible before the blow-pipe. 

 2. Analysis. 

 By CHENEVIX. By LAUGIER. 



white variety. rose-red variety. 



Silica . 42-5 . 43.0 . 42-0 



Alumina . 37-5 . 34-5 . 34-0 



Lime . 15-0 . 15-6 . 15-0 



Soda . 0-0 . 2-6 . 3-3 



Oxide of iron . 3-0 . 1-0 . 3-2 



Water . 0-0 . 1-0 . 1-0 



3. It occurs in the Carnatic, associated with Feldspar, Hornblende, 

 Garnet, Corundum, Epidote and Magnetic-Iron. 



4. It is nearly related to, if not identical with, Labradorite. 



INDICOLITE. (See Tourmaline.) 



IODIC MERCURY. 



In spots of a fine lemon-yellow color, in the variegated sand- 

 stone of Casas viegas, Mexico. In the air, as well as in ammonia, 

 it changes to black. It resembles the artificial protiodide of mer- 

 cury. 



IODIC SILVER. Monotomous Pearl-Kerate. 



Massive : in thin plates. 



Color greyish white, or silver-white. Exposed to the 

 air, it changes to lavender-blue. Lustre resinous. Streak 

 semi-metallic. Translucent. 



Soft, flexible. 



1. Before the blow-pipe, on charcoal, it instantly melts, and produces 

 a smoke which tinges the flame of a beautiful violet color, globules of 

 silver at the same time appearing upon the charcoal. 



2. It is found at Albarradon, near Mazapil in Mexico, and occurs in 

 thin veins in steatite. 



