Albite

Albite is a plagioclase feldspar mineral. It is the sodium endmember of the plagioclase solid solution series. As such it represents a plagioclase with less than 10% anorthite content. The pure albite endmember has the formula NaAlSi3O8. It is a tectosilicate.Albite crystallizes with triclinic pinacoidal forms. Its specific gravity is about 2.62 and has a Mohs hardness of 6. Albite almost always exhibits crystal twinning often as minute parallel striations on the crystal face. Albite often occurs as fine parallel segregations alternating with pink microcline in perthite as a result of exolution on cooling. It occurs in granitic and pegmatite masses and also in some hydrothermal vein deposits.
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Noun
1. a widely distributed rock-forming feldspar
(synonym) white feldspar
(hypernym) plagioclase, oligoclase

n. albite, a widely distributed rock-forming feldspar

(n.)
A mineral of the feldspar family, triclinic in crystallization, and in composition a silicate of alumina and soda. It is a common constituent of granite and of various igneous rocks. See Feldspar.
  

General Information:
 Chemical Formula:
NaAlSi3O8
 Composition:
(Molecular Weight = 263.02 gm)
Sodium 8.30 % Na
Calcium 0.76 % Ca
Aluminum 10.77 % Al
Silicon 31.50 % Si
Oxygen 48.66 % O 
 Empirical Formula:
Na0.95Ca0.05Al1.05Si2.95O8
 Environment:
Magmatic and pegmatitic rocks.
 Locality:
TL: USA, VA, Amelia. Bourg d'Oisans and Isere, France.
 Name Origin:
From the Latin, albus, in allusion to the common color.
Physical Properties:
 Cleavage:
[001] Perfect, [010] Good
 Color:
white, gray, greenish gray, bluish green, or gray.
 Density:
2.61 - 2.63, Average = 2.62
 Diaphaniety:
Transparent to translucent to subtranslucent
 Habits:
Blocky - Crystal shape tends to be equant (e.g. feldspars)., Striated - Parallel lines on crystal surface or cleavage face., Granular - Generally occurs as anhedral to subhedral cryst als in matrix.
 Hardness:
7 - Quartz
 Luminescence:
None.
 Luster:
Vitreous (Glassy)
 Streak:
white
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