Anorthoclase

Microcline (KAlSi3O8) is an important igneous rock forming tectosilicate mineral. It is a potassium-rich alkali feldspar. Microcline typically contains minor amounts of sodium. It is common in granite and pegmatites. Microcline forms during slow cooling of orthoclase; it is stable at lower temperatures than orthoclase. Sanidine is a polymorph of alkali feldspar stable at yet higher temperature. Microcline may be clear, white, pale-yellow, brick-red, or green; it is generally characterized by cross-hatch twinning that forms as a result of the transformation of monoclinic orthoclase into triclinic microcline.
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General Information:
 Chemical Formula:
(Na,K)AlSi3O8
 Composition:
(Molecular Weight = 266.25 gm)
Potassium 3.67 % K 
Sodium 6.48 % Na
Aluminum 10.13 % Al
Silicon 31.65 % Si
Oxygen 48.07 % O 
 Empirical Formula:
Na0.75K0.25AlSi3O8
 Environment:
Andesitic lavas.
 Locality:
Pantelleria. Southwest of Sicily.
Physical Properties:
 Cleavage:
[001] Perfect, [010] Good
 Color:
colorless, green, gray, gray pink, or yellow.
 Density:
2.57 - 2.6, Average = 2.58
 Diaphaniety:
Transparent
 Habits:
Disseminated - Occurs in small, distinct particles dispersed in matrix., Granular - Generally occurs as anhedral to subhedral crystals in matrix.,
 Hardness:
6 - Orthoclase
 Luster:
Vitreous (Glassy)
 Streak:
white
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ANORTOCLASIO

B: (Kimia) anortoklas
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