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Outline for Determination of Minerals. 



I. Scale of Hardness. 



1. Talc and Grypsum. Very soft. Can be scratched 

 with 'finger nail, or very easily with a knife. 



2. Calcite and Muorite. Soft. Cannot be scratched 

 with finger nail, but 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; scratches glass. Topaz scratches quartz. 



5. Corundum and Diamond. Corundum scratched by 

 diamond and itself; diamond not scratched by any other 

 mineral. 



II. Specific Grravity. 



1. Weight in air. 



2. Weight in water. 



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

 water. 



m. Form. 



1. External. Surface— grape like. Porous— mineral 

 incrustations formed from solutions. Stalactitic— hang- 

 ing from under surface of rock, cone-shaped. Stalagmitic 

 —formed on floors of caverns from dripping water. Strati- 

 fied — deposited in layers. 



2. 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. 



