The Mineral Identification Key Copper, Michigan, Seaman Museum specimen

Tenacity refers to a mineral’s resistance to breaking, bending, or otherwise being deformed.  A mineral may be brittle, easily broken or crushed to powder; malleable, easily hammered into thin sheets (such as copper or gold); sectile, easily cut with a knife; flexible, easily bent without breaking and then staying bent; or elastic, bending but resuming its original shape once pressure is released.

 
Flexible - Bent stibnite crystal (probably in the act of mining), China,  5cm across

Tenacity is particularly useful in telling some of the metallic minerals apart.  Gold is malleable, pyrite (and most other look-a-likes) is not. Gold is also sectile and – in thin sheets – flexible.  Galena is brittle, while platinum is malleable and sectile.

Flexibility and elasticity can be useful with minerals that are commonly found as flakes or acicular crystals.  Chlorite flakes and thin crocoite crystals can be bent, and they will stay bent.  Mica sheets bend and then snap back to their original shape when released.

 

[ Table of Contents ] [ Introduction ] [ Identification Kit ] [ Mineral Properties ] [ Environments & Associations ] [ In Conclusion ] [ The Mineral ID Key ]

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