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Andesine

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Formula:
(Na,Ca)[Al(Si,Al)Si2O8]
System:
Triclinic
Colour:
White, gray, green, ...
Lustre:
Sub-Vitreous, Pearly
Hardness:
6 - 6½
Member of:
Name:
For the Andes Mountains of South America where it is abundant in the lavas.
A variety of Albite

A plagioclase feldspar with an albite : anorthite molar ratio ranging from 50 : 50 to 70 : 30.

Originally described from Marmato Mine, Marmato, Cauca, Chocó Department, Colombia.
Crystals rare, to 2 cm; commonly massive, cleavable, or granular. Twinning: Commonly twinned after Albite, Pericline, and Carlsbad laws. Also twinned after a law similar to the Manebach law.

Visit gemdat.org for gemological information about Andesine.

Classification of Andesine

9.FA.35

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

Geological Setting:
Widespread in igneous rocks of intermediate silica content, as syenites and andesites. Characteristic of granulite to amphibolite facies metamorphism, commonly as antiperthite; as detrital grains in sedimentary rocks.

Physical Properties of Andesine

Sub-Vitreous, Pearly
Diaphaneity (Transparency):
Transparent, Translucent
Colour:
White, gray, green, yellow, flesh-red.
Streak:
White
Hardness (Mohs):
6 - 6½
Tenacity:
Brittle
Cleavage:
Perfect
Perfect on {001}, less perfect on {010}; {110} also observed.
Fracture:
Irregular/Uneven, Conchoidal

Crystallography of Andesine

Crystal System:
Triclinic

Optical Data of Andesine

Type:
Biaxial (+/-)
RI values:
nα = 1.543 - 1.554 nβ = 1.547 - 1.559 nγ = 1.552 - 1.562
2V:
Measured: 76° to 83°, Calculated: 78° to 84°
Max Birefringence:
δ = 0.009
Image shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:
Low
Dispersion:
none

Chemical Properties of Andesine

Formula:
(Na,Ca)[Al(Si,Al)Si2O8]
Essential elements:
All elements listed in formula:

Relationship of Andesine to other Species

Member of:
Other Members of Group:
AlbiteNaAlSi3O8
Amazonite
AnorthiteCaAl2Si2O8
Anorthoclase(Na,K)AlSi3O8
BanalsiteBaNa2[Al2Si2O8]2
Buddingtonite(NH4)AlSi3O8
Bytownite(Ca,Na)[Al(Al,Si)Si2O8]
CelsianBaAl2Si2O8
DmisteinbergiteCaAl2Si2O8
Hyalophane(K,Ba)[Al(Si,Al)Si2O8]
Labradorite(Ca,Na)[Al(Al,Si)Si2O8]
MicroclineKAlSi3O8
Oligoclase(Na,Ca)[Al(Si,Al)Si2O8]
OrthoclaseKAlSi3O8
ParacelsianBaAl2Si2O8
ReedmergneriteNa[BSi3O8]
SanidineKAlSi3O8
Slawsonite(Sr,Ca)Al2Si2O8
StronalsiteSrNa2[Al2Si2O8]2
SvyatoslaviteCaAl2Si2O8
9.FA.05KaliophiliteKAlSiO4
9.FA.05KalsiliteKAlSiO4
9.FA.05Nepheline(Na,K)AlSiO4
9.FA.05Panunzite(K,Na)AlSiO4
9.FA.05Trikalsilite(K,Na)AlSiO4
9.FA.05Yoshiokaite(Ca,Na)[Al(Al,Si)O4]
9.FA.05MegakalsiliteKAlSiO4
9.FA.10MalinkoiteNaBSiO4
9.FA.15VirgiliteLiAlSi2O6
9.FA.25LisitsyniteKBSi2O6
9.FA.30AdulariaKAlSi3O8
9.FA.30Anorthoclase(Na,K)AlSi3O8
9.FA.30Buddingtonite(NH4)AlSi3O8
9.FA.30CelsianBaAl2Si2O8
9.FA.30Hyalophane(K,Ba)[Al(Si,Al)Si2O8]
9.FA.30MicroclineKAlSi3O8
9.FA.30OrthoclaseKAlSi3O8
9.FA.30SanidineKAlSi3O8
9.FA.30Rubicline(Rb,K)AlSi3O8
9.FA.30MonalbiteNaAlSi3O8
9.FA.35AlbiteNaAlSi3O8
9.FA.35AnorthiteCaAl2Si2O8
9.FA.35Bytownite(Ca,Na)[Al(Al,Si)Si2O8]
9.FA.35Labradorite(Ca,Na)[Al(Al,Si)Si2O8]
9.FA.35Oligoclase(Na,Ca)[Al(Si,Al)Si2O8]
9.FA.35ReedmergneriteNa[BSi3O8]
9.FA.40ParacelsianBaAl2Si2O8
9.FA.45SvyatoslaviteCaAl2Si2O8
9.FA.45KumdykoliteNaAlSi3O8
9.FA.50Slawsonite(Sr,Ca)Al2Si2O8
9.FA.55LisetiteCaNa2Al4Si4O16
9.FA.60BanalsiteBaNa2[Al2Si2O8]2
9.FA.60StronalsiteSrNa2[Al2Si2O8]2
9.FA.65DanburiteCaB2Si2O8
9.FA.65MaleeviteBaB2Si2O8
9.FA.65PekoviteSrB2Si2O8
9.FA.70Lingunite(Na,Ca)AlSi3O8
9.FA.75KokchetaviteKAlSi3O8

Other Names for Andesine

Name in Other Languages:
German:Andesin
Simplified Chinese:中性长石
中长石

Other Information

Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for Andesine

Reference List:
Richet, P. and Bottinga, Y. (1984b) Anorthite, andesine, wollastonite, diopside, cordierite, and pyrope thermodynamics of melting, glass transitions, and properties of the amorphous phases. Earth and Planetary Science Letters: 67: 415-432.

Internet Links for Andesine

Localities for Andesine

map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.
Mineral and/or Locality  
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