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OUTLINE FOR DETERMINATION OF MINERALS. 



Scale of Hardness. 



1. Talc and Gypsum. Very soft. Can be scratched with finger 

 ail, or very easily with a knife. 



2. Calcite and Fluorite. Soft. Cannot be scratched with finger 

 nail, bat easily scratched with knife. 



3. Apatite and Orthoclase. Hard, Not easily scratched with 

 knife; scratches glass. 



4. Quartz and Topaz. Very hard. Cannot be scratched with knife; 

 cratches glass. Topaz scratches quartz. 



5. Corundum and Diamond. Corundum scratched by diamond 

 d itself; diamond not scratched by any other mineral. 



Specific Gravity. 

 1. Weight in air. 

 '2. Weight in water. 

 3. Specific Gravity weight in air; loss of weight in water. 



III. Form. 



1. External. Surface grape like. Porous mineral incrustations 

 formed from solutions. Stalactitic hanging from under surface of 

 rock, cone-shaped. Stalagmitic formed on floors of caverns from 

 dripping water. Stratified deposited in layers. 



Internal. Granular, coarse or fine small crystals. Compact- 

 crystals invisible to unaided eye. 



IV. Tenacity. 



1. Brittle breaks easily. 



2. Malleable flattens into thin sheets under hammer. 



3. Sectile may be cut into thin slices. 



4. Flexible retains its form when bent. 



5. Elastic comes back in its original form when bent. 

 Lustre. 



1. Metallic, as in Metals. 



2. Non-metallic vitreous, as in glass. Pearly, as in pearl. Resin- 

 us, as in sulphur, sphalerite, resins. Pitchy, as in cannel coal, 

 ilky or satiny, as in satin spar. Greasy, or waxy, as in serpentine, 

 ull, as in chalk. 



I. Streak. Color obtained by rubbing mineral over surface of a 

 piece of ground glass or file. 



