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Orthoclase  (Kspar)KAlSi3O8

Class: Silicate
Subclass: Framework
Hardness: 6 - 6.5
Density: 2.6
Streak: White
Lustre: Vitreous
Habit: Polysynthetic twinning
Colours: Pinky-white

  Crystal System: Orthorhombic
Cleavage: Perfect
Fracture: Subconchoidal
Magnetism: None
Reaction with HCl: None

Identification in hand sample:
Colour and evidence of exsolution with plagioclase.

Associations:
Very common in granite, granodiorite, syenite and related felsic rocks.

Comments:
Orthoclase is the potassic variety of feldspar.

  

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