Mineral 1.0Test your knowledge of specific minerals

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Plagioclase  (Anothite (Ca), Albite (Na))CaAl2Si2O8

Class: Silicate
Subclass: Framework
Hardness: 6 - 6.5
Streak: White
Lustre: Vitreous
Colours: White and gray

  Crystal System: Triclinic
Cleavage: Good
Magnetism: None
Reaction with HCl: Weak

Identification in hand sample:
Parallel striations and white-gray colour separates this mineral from orthoclase (Kspar).

Associations:
Most abundant mineral in the Earth's crust.

Industrial / ecomonic uses:
Concrete, filler, sand, gravel, etc.

Comments:
Calcium-rich plag is called Anorthite. Sodium-rich plag is called Albite. Twinning occurs.

  

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