Mohs scale
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The Mohs scale of mineral hardness is a qualitative ordinal scale, from 1 to 10, characterizing scratch resistance of minerals through the ability of harder material to scratch softer material.
Mohs hardness kit, containing one specimen of each mineral on the ten-point hardness scale
Talc block
Gypse Arignac
Calcite sample 2
Rutile
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Rutile is an oxide mineral composed of titanium dioxide, the most common natural form of TiO2. Rarer polymorphs of TiO2 are known, including anatase, akaogiite, and brookite.
Rutile in quartz
Milled rutile
Acicular crystals of rutile protruding from a quartz crystal