Mineral 1.0: Plagioclase

Mineral 1.0

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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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