GUIDE 'I'n TI1K MINBRALOGiC COLLECTION^ 



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Stephanite (brittle silver ore) Ag : ,SbS 4 



Stepbanite is a sult'am iuioni I »- of silver containing Hi.:'.', sui 

 fur, 1 .").!'', antimony and 68.5$ silver. 



Orthorhombic crystals in short prismatic and tabular forms 

 are frequently found. The mineral usually occurs in fine grained 

 masses of an iron-black color and metallic luster. Also in dis- 

 seminated grains. 



Stephanite occurs in veins with other silver ores, the principal 

 localities being those mentioned under argentite, pyrargyrite, 



etc. 



Enargite Cu..AsS 4 



Enargite is a sulfarsenite of copper containing 3"2.6^ sulfur, 

 19.1$ arsenic and 48.3$ copper. 



Orthorhombic crystals are sometimes met with; these are pris- 

 matic in habit and striated parallel to the vertical axis. Enar- 

 gite commonly occurs in columnar or granular masses. It is 

 black in color and has a metallic luster. 



Enargite is found associated with other copper minerals in 

 Chile, Peru and Mexico; also iu South Carolina, Colorado, Utah, 

 California and in the Tintic district of Montana. 



It is an ore of copper. 



HALOIDS 



OHLORIDS, BROMIDS, IODIDS. FLUORIDS 

 Halite (rock salt) NaCl 



Halite or common salt is the chlorid of sodium and contains 

 :!'.). V, chlorin and 60.6$ sodium. It seldom occurs perfectly pure 

 but is commonly mixed with calcium sul- 

 fate, calcium chlorid. magnesium chlorid 

 and magnesium sulfate. 



Halite is isometric and usually crystallizes 

 in cubes (pi. 17,). which often show distortion 

 and cavernous faces, as in tig. 17(>. Masses 

 with perfoci cubic cleavage are common as 



Well as a fibrous variety which is said to be 



pseudomorphous after fibrous gypsum. Halite has a vitreous 

 luster and when pure is colorless ami transparent; yellow, red. 

 brown, blue and purple shades are due to impurities, as is also 

 the translucency accompanying these variations in color. It has 

 a charaderist ic saline taste. 



