Albite (variety of Feldspar)
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Albite was named in 1815 by Johan Gottlieb Gahn and Jöns Jacob Berzelius from the Latin word albus, meaning white, in allusion to its typical color. Albus is also the root for the word albino.

Discovered in 1815; IMA status: Valid (pre-IMA; Grandfathered)

Chemistry

Chemical Formula:

Na[AlSi₃O₈]

Sodium Aluminum Silicate

Molecular Weight:

263.02 gm

Composition:

Sodium

8.30 %

Na

11.19 %

Na₂O

Calcium

0.76 %

Ca

1.07 %

CaO

Aluminum

10.77 %

Al

20.35 %

Al₂O₃

Silicon

31.50 %

Si

67.39 %

SiO₂

Oxygen

48.66 %

O

100.00 %

100.00 %

= TOTAL OXIDE

Classification

Mineral Classification:

Silicates (Germanates)

Strunz 8th Ed. ID:

8/J.07-20

Nickel-Strunz 10th Ed. ID:

9.FA.35

9 : SILICATES (Germanates)
F : Tektosilicates without zeolitic H₂O
A : Tektosilicates without additional non-tetrahedral anions

Related to:

Feldspar Group. Plagioclase Series. Na-rich end member of the Albite - Anorthite Series. Anorthoclase - Anorthite - Banalcite Series. Low- and high-temperature structural modifications are recognized.

Members of Group:

Feldspar Group: Albite, Amazonite, Andesine, Anorthite, Anorthoclase, Banalsite, Buddingtonite, Bytownite, Celsian, Dmisteinbergite, Hyalophane, Labradorite, Microcline, Oligoclase, Orthoclase, Paracelsian, Reedmergnerite, Sanidine, Slawsonite, Stronalsite, Svyatoslavite 

Varieties:

Albite Moonstone, Andesine, Cleavelandite, High Albite, Lazur-Feldspath, Low Albite, Oligoclase, Oligoclase-Albite, Pericline, Peristerite

Synonyms:

Acid Plagioclase, Analbite (of Alling), Cryptoclase, Cryptose, Hyposclerite, Kieselspath, Natro-Feldspat, Olafite, Sodaclase, Soda Feldspar, Tetartine, White Feldspar, White Schorl, Zygadite

Crystal Data

Crystallography:

Triclinic - Pinacoidal

Crystal Habit:

Crystals commonly tabular || {010}, may be curved, to 3 cm; divergent aggregates, granular, cleavable, massive.

Twinning:

Common around [010] or {010}, giving polysynthetic striae on {001} or {010}; many other laws, contact, simple and multiple.

Physical Properties

Cleavage:

[001] Perfect, [010] Very Good, {110} Imperfect

Fracture:

Irregular/Uneven, Conchoidal

Tenacity:

Brittle

Moh's Hardness:

6.0 - 6.5

Density:

2.6 - 2.65 (g/cm³)

Luminescence:

Fluorescent; cherry red under SW UV, white under LW UV 

Radioactivity:

Not Radioactive

Optical Properties

Color:

Colorless, white to gray, bluish, greenish, reddish; may be chatoyant

Transparency:

Transparent to translucent

Luster:

Vitreous; pearly on cleavages

Refractive Index:

1.528 - 1.542  Biaxial ( + ) (low); Biaxial ( - ) (high)

Birefringence:

0.0090 - 0.0100

Dispersion:

Weak; r < v

Pleochroism:

None

Occurances

Geological Setting:

A major constituent of granites and granite pegmatites, alkalic diorites, basalts, and in hydrothermal and alpine veins. A product of potassium metasomatism and in low-temperature and low-pressure metamorphic facies and in some schists. Detrital and authigenic in sedimentary rocks.

Common Associations:

Biotite, Hornblende, Orthoclase, Muscovite, Quartz

Common Impurities:

Ca, K, Mg

Type Locality:

Finnbo (Finbo), Falun, Dalarna, Sweden

Year Discovered:

1815

View mineral photos:

Albite Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Albite is a rare member of the Plagioclase Feldspars of the Feldspar Group of minerals that includes Albite, Amazonite, Andesine, Anorthite, Bytownite, Hyalophane, Labradorite, Moonstone, Oligoclase, Orthoclase, Sanidine and Sunstone. The Plagioclase Feldspars form a series between Albite and Anorthite. Albite is the sodium-rich end member while Anorthite is the calcium-rich end member and Oligoclase is the intermediate member. Albite is also an end member of the alkali or K-Feldspars. A variety of Albite called Cleavelandite is rarely found as white inclusions in Quartz. Albite is considered a fluorescent mineral because it fluoresces cherry red under SW UV light and white under LW UV light.

Albite was named in 1815 by Johan Gottlieb Gahn and Jöns Jacob Berzelius from the Latin word albus, meaning white, in allusion to its typical color. Albus is also the root for the word albino.

Sources of Albite are: Minas Gerais, Southeast Region, Brazil; Bancroft District, Hastings County, Ontario, Canada; Wicklow Township, Hastings County, Ontario, Canada; Poudrette quarry, Mont Saint-Hilaire, Rouville County, Québec, Canada; Skardu Road, Skardu District, Baltistan, Northern Areas, Pakistan; Hawk Mine, Hawk-Bakersville, Spruce Pine District, Mitchell County, North Carolina, USA.
 

  
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