92 DESCRIPTIONS OF MINERALS. 



2. Boron Group. — The chief oxide a trioxide, its formula 

 R 2 3 . Includes compounds of Boron with oxygen. 



3. Arsenic Group. — The chief oxide a pentoxide, its formula 

 Bj0 5 . Includes Arsenic and arsenic sulphides and oxides ; An- 

 tiDiony and antimony sulphide, arsenide and oxides; Bismuth 

 and bismuth sulphide, telluride and oxide. 



4. Carbon Group. — The chief oxide a dioxide, its formula 

 R G 2 . Includes Carbon (Diamond, Graphite) and carbon diox- 

 ide. (Quartz, Si O i5 belongs here chemically, but is placed with 

 the Silicates.) 



II. Basic Division. 



Gold ; Silver ; Platinum and Iridium ; Palladium ; Quick- 

 silver ; Copper ; Lead ; Zinc ; Cadmium ; Tin ; Titanium ; Co- 

 balt and Nickel; Uranium; Iron; Manganese; Aluminium; 

 Cerium, Yttrium, Lanthanum, Didymium and Erbium ; Mag- 

 nesium; Calcium; Barium and Strontium; Potassium and 

 Sodium ; Ammonium ; Hydrogen. 



III. Silica and Silicates. 



1. Silica. 



2. Anhydrous Silicates. 



1. Bisilicates. 



2. Unisilicates. 



3. Subsilicates. 



3. Hydrous Silicates. 



1 . General section of Hydrous Silicates. 



2. Zeolite section. 



3. Margarophyllite section. 



IV. Hydrocarbon Compounds. 



1. Oils, Resins, Wax. 



2, Asphaltum, Coals. 



General Remarks on Ores. 



An ore, in the mineralogical sense of the word, is a mineral 

 compound in which a metal is a prominent constituent. In the 



