Fro example, Corundum (Sapphire and Ruby) was used to scratch Apatite. Corundum left a scratch on the surface of Apatite, and so this mineral should sit higher on the scale. The most important number on this scale of 7. Why? 7 is the hardness of Quartz, which is the hardest mineral that is commonly air born. It is important to have jewelery ...
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