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Metallic Minerals denned. 

 Minerals are metallic when 

 1. The Specific Gravity exceeds 5.0. 

 % The streak, or scraped surface exhibits metallic lustre. 



3. They can be reduced to the metallic state, on charcoal, by 

 the flame of a blow-pipe, with or without borax. 



4. They possess ductility or malleability, with high specific 

 gravity. 



5. They exhibit the hackly fracture. 



€. The color they communicate to borax before the blow-pipe is 

 a vivid green which does not vanish on cooling, a smalt or 

 sky blue, a hyacinth red, violet blue, or amethystine. 



7. They are volatilized entirely before the blow-pipe, the specific 

 gravity being above 2.5. 



8. They are volatilized in part, exhaling the odor of arsenic, or 

 antimony, or selenium, or tellurium. 



9. They are magnetic, either before or after roasting on charcoal, 

 the specific gravity being above 4.5. 



10. When they impart a styptic metallic flavor to the palate. 

 Minerals are probably metallic when 



1. The specific gravity exceeds 4.0. — The exceptions are given, 

 sapphire (green), automolite, gadolenite, some varieties of the 

 garnet, with sulphate and carbonate of barytes. 



2. When they communicate any color to borax before the blow- 

 pipe. The exceptions, however, are many, as garnet, horn- 

 blende, actynolite, augite, hyperstene, chlorite, lava, pumice, 

 basalt, cinnamon stone, idocrase, common schorl, hauyne, 

 colophonite, boracite, &c. &c. in all of which some metallic 

 oxide, usually of iron, affords the coloring principle. 



3. They are volatilized entirely or almost entirely before the 

 blow-pipe. The exceptions are confined to the combustible 

 and saline classes, as sulphur, coal, muriate of ammonia, &c. 



4. They exhibit the semi or imperfect metallic lustre. The ex- 

 ceptions are mica, talc, hyperstene, anthophyllite, aphsite, 

 bronzite, sometimes schiller spar, and olivine. 



5. They exhibit magnetism, either before or after roasting on 

 charcoal — the exceptions are sometimes basalt, lava, pumice, 

 hornblende, garnet, &c. also some rocks or portions of them. 



