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Sanidine

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Formula:
KAlSi
 
3
O
 
8
System:MonoclinicColour:Colourless, white, grey, ...
Lustre:VitreousHardness:6
Member of:Feldspar Group
Name:From the Greek "sanis" for "little plate" and "idos" for "to see."


Feldspar Group.
Common in volcanic rocks.

See also the other potassium-dominant feldspars microcline and orthoclase.

Visit gemdat.org for gemological information about Sanidine. Currently in public beta-test.

Classification of Sanidine

IMA status:Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
Strunz 8th edition ID:8/J.06-20
Nickel-Strunz 10th (pending) edition ID:9.FA.30

9 : SILICATES (Germanates)
F : Tektosilicates without zeolitic H2O
A : Tektosilicates without additional non-tetrahedral anions
Dana 8th edition ID:76.1.1.2

76 : TECTOSILICATES Al-Si Framework
1 : Al-Si Framework with Al-Si frameworks
Hey's CIM Ref.:16.3.7

16 : Silicates Containing Aluminum and other Metals
3 : Aluminosilicates of K
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Type Occurrence of Sanidine

Type Locality:Drachenfels, Königswinter, Siebengebirge, North Rhine-Westphalia, Germany
Year of Discovery:1808

Occurrences of Sanidine

Geological Setting:Acidic volcanic rocks

Physical Properties of Sanidine

Lustre:Vitreous
Diaphaneity (Transparency):Transparent, Translucent
Colour:Colourless, white, grey, yellowish white, or reddish white
Streak:White
Hardness (Mohs):6
Tenacity:Brittle
Cleavage:Perfect
{001} Perfect, {010} distinct
Parting:{100}
Fracture:Irregular/Uneven, Conchoidal
Density (measured):2.56 - 2.62 g/cm3
Density (calculated):2.56 g/cm3

Crystallography of Sanidine

Crystal System:Monoclinic
Class (H-M):2/m - Prismatic
Space Group:B2/m {B1 1 2/m} {C2/m} {C1 2/m 1}
Cell Parameters:a = 8.6Å, b = 13.03Å, c = 7.17Å
β = 116.03°
Ratio:a:b:c = 0.66 : 1 : 0.55
Unit Cell Volume:V 721.96 ų (Calculated from Unit Cell)
Morphology:Tabular with square cross section
Twinning:Carlsbad - common
Baveno, Manebach - rarer
Comment:High sanidine forms a series with high albite

Optical Data of Sanidine

Type:Biaxial (-)
RI values: nα = 1.518 - 1.525 nβ = 1.523 - 1.530 nγ = 1.525 - 1.531
2V:Measured: 60° , Calculated: 48° to 64°
Maximum Birefringence:δ = 0.007

Chart shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:Low
Dispersion:r < v distinct

Chemical Properties of Sanidine

Formula:
KAlSi
 
3
O
 
8
Simplified for copy/paste:KAlSi3O8
Essential elements:Al, K, O, Si
All elements listed in formula:Al, K, O, Si
Common Impurities:Fe,Ca,Na,H2O

Relationship of Sanidine to other Species

Member of:Feldspar Group
Other Members of Group:

- +
Albite
NaAlSi
 
3
O
 
8
Amazonite
Andesine
(Na,Ca)[Al(Si,Al)Si
 
2
O
 
8
]
Anorthite
CaAl
 
2
Si
 
2
O
 
8
Anorthoclase
(Na,K)AlSi
 
3
O
 
8
Banalsite
BaNa
 
2
[Al
 
2
Si
 
2
O
 
8
]
 
2
Buddingtonite
(NH
 
4
)AlSi
 
3
O
 
8
Bytownite
(Ca,Na)[Al(Al,Si)Si
 
2
O
 
8
]
Celsian
BaAl
 
2
Si
 
2
O
 
8
Dmisteinbergite
CaAl
 
2
Si
 
2
O
 
8
Hyalophane
(K,Ba)[Al(Si,Al)Si
 
2
O
 
8
]
Labradorite
(Ca,Na)[Al(Al,Si)Si
 
2
O
 
8
]
Microcline
KAlSi
 
3
O
 
8
Oligoclase
(Na,Ca)[Al(Si,Al)Si
 
2
O
 
8
]
Orthoclase
KAlSi
 
3
O
 
8
Paracelsian
BaAl
 
2
Si
 
2
O
 
8
Reedmergnerite
Na[BSi
 
3
O
 
8
]
Slawsonite
(Sr,Ca)Al
 
2
Si
 
2
O
 
8
Stronalsite
SrNa
 
2
[Al
 
2
Si
 
2
O
 
8
]
 
2
Svyatoslavite
CaAl
 
2
Si
 
2
O
 
8
Related Minerals - Nickel-Strunz Grouping):

- +
9.FA.05Kaliophilite
KAlSiO
 
4
9.FA.05Kalsilite
KAlSiO
 
4
9.FA.05Nepheline
(Na,K)AlSiO
 
4
9.FA.05Panunzite
(K,Na)AlSiO
 
4
9.FA.05Trikalsilite
(K,Na)AlSiO
 
4
9.FA.05Yoshiokaite
(Ca,Na)[Al(Al,Si)O
 
4
]
9.FA.05Megakalsilite
KAlSiO
 
4
9.FA.10Malinkoite
NaBSiO
 
4
9.FA.15Virgilite
LiAlSi
 
2
O
 
6
9.FA.25Lisitsynite
KBSi
 
2
O
 
6
9.FA.30Adularia
KAlSi
 
3
O
 
8
9.FA.30Anorthoclase
(Na,K)AlSi
 
3
O
 
8
9.FA.30Buddingtonite
(NH
 
4
)AlSi
 
3
O
 
8
9.FA.30Celsian
BaAl
 
2
Si
 
2
O
 
8
9.FA.30Hyalophane
(K,Ba)[Al(Si,Al)Si
 
2
O
 
8
]
9.FA.30Microcline
KAlSi
 
3
O
 
8
9.FA.30Orthoclase
KAlSi
 
3
O
 
8
9.FA.30Rubicline
(Rb,K)AlSi
 
3
O
 
8
9.FA.30Monalbite
NaAlSi
 
3
O
 
8
9.FA.35Albite
NaAlSi
 
3
O
 
8
9.FA.35Andesine
(Na,Ca)[Al(Si,Al)Si
 
2
O
 
8
]
9.FA.35Anorthite
CaAl
 
2
Si
 
2
O
 
8
9.FA.35Bytownite
(Ca,Na)[Al(Al,Si)Si
 
2
O
 
8
]
9.FA.35Labradorite
(Ca,Na)[Al(Al,Si)Si
 
2
O
 
8
]
9.FA.35Oligoclase
(Na,Ca)[Al(Si,Al)Si
 
2
O
 
8
]
9.FA.35Reedmergnerite
Na[BSi
 
3
O
 
8
]
9.FA.40Paracelsian
BaAl
 
2
Si
 
2
O
 
8
9.FA.45Svyatoslavite
CaAl
 
2
Si
 
2
O
 
8
9.FA.45Kumdykolite
NaAlSi
 
3
O
 
8
9.FA.50Slawsonite
(Sr,Ca)Al
 
2
Si
 
2
O
 
8
9.FA.55Lisetite
CaNa
 
2
Al
 
4
Si
 
4
O
 
16
9.FA.60Banalsite
BaNa
 
2
[Al
 
2
Si
 
2
O
 
8
]
 
2
9.FA.60Stronalsite
SrNa
 
2
[Al
 
2
Si
 
2
O
 
8
]
 
2
9.FA.65Danburite
CaB
 
2
Si
 
2
O
 
8
9.FA.65Maleevite
BaB
 
2
Si
 
2
O
 
8
9.FA.65Pekovite
SrB
 
2
Si
 
2
O
 
8
9.FA.70Lingunite
(Na,Ca)AlSi
 
3
O
 
8
9.FA.75Kokchetavite
KAlSi
 
3
O
 
8
Related Minerals - Hey's Index Grouping:

- +
16.3.1Lithosite
K
 
6
Al
 
4
Si
 
8
O
 
25
· 2H
 
2
O
16.3.2Kaliophilite
KAlSiO
 
4
16.3.3Kalsilite
KAlSiO
 
4
16.3.4Leucite
K(AlSi
 
2
O
 
6
)
16.3.5Microcline
KAlSi
 
3
O
 
8
16.3.6Orthoclase
KAlSi
 
3
O
 
8
16.3.8Muscovite
KAl
 
2
(AlSi
 
3
O
 
10
)(OH)
 
2

Other Names for Sanidine

Synonyms:
Glassy FeldsparGränzeriteRhyacoliteRiacolite
Other Languages:
Finnish:Sanidiini
German:Sanidin
Glasiger Feldspath
Gränzerit
Rhyacolit
Riacolit
Hebrew:סנידין
Italian:Sanidino
Japanese:サニディン
Russian:Санидин
Simplified Chinese:透长石
Spanish:Gränzerita
Rhyacolita
Riacolita
Traditional Chinese:透長石
Varieties:
AzuliciteBarium-SanidineCitron Feldspar

Other Information

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

References for Sanidine

Reference List:

- +
Klaproth, M.H. (1810): Chemische Untersuchung des glasigen Feldspaths vom Drachenfels, Beiträge zur chemischen Kenntniss der Mineralkörper, Fünfter Band, Rottmann Berlin, 12-18

Onorato E., Penta M., Sgarlata F. -(1963) Struttura del sanidino. Periodico di Mineralogia – Roma pp. 1-34.

Scott, R.B., Bachinski, S.W., Nesbitt, R.W., and Scott, M.R. (1971) Rate of Al-Si ordering in sanidines from an ignimbrite cooling unit. American Mineralogist: 56: 1208-1221.

Bertelmann, D., Förtsch, E., and Wondratscher, H. (1985) Zum Temperverhalten von Sanidin: die Ausnahmerolle der Eifelsanidin-Megakristalle. Neues Jahrbuch für Mineralogie, Abhandlungen: 152: 123-141.

Gering, E. (1985) Silizium/Aluminium-Ordnung und Kristallperfektion von Sanidinen. Dissertation, University of karlsruhe, Karlsruhe, Germany.

Bertelmann, D., Walther, J., and Wondratscher, H. (1987) Annealing-induced inclusions and transformation behaviour of Eifel sanidines. Terra Cognita: 7: 257-258.

Bernotat-Wulf, H., Bertelmann, D., and Wondratscher, H. (1988) The annealing behavour of Eifel sanidine (Volkesfeld). III. The influence of the sample surface and sample size on the order-disorder transformation rate. Neues Jahrbuch für Mineralogie, Monatshefte 1988: 504-515.

Ferguson, R.B., Ball, N.A., and Cerny, P. (1991) Structure refinement of an adularian end-member high sanidine from the Buck Claim pegmatite, Bernic Lake, Manitoba. Canadian Mineralogist: 29: 543-552.

Kroll, H. and Knitter, R. (1991) Al, Si exchange kinetics in sanidine and anorthoclase and modeling of rock cooling paths. American Mineralogist: 76: 928-941.

Widder, W. (1991) Röntgentopographische Untersuchungen am Sanidin von Volkesfeld und Orthoklas von Madagaskar. Diplomarbeit an der Fakultät für Physik, Universität Karlsruhe, Karlsruhe, Germany.

Widder, W., Wondratscher, H., Fehlmann, M., and Klapper, H. (1994) X-ray topographic study of Eifel sanidine (Volkesfeld). Zeitschrift für Kristallographie: 209: 206-209.

Mineralogical Record (1995): 26: 222.

Kimata, M., Saito, S., Shimizu, M., Iida, I., and Tomoaki, M. (1996) Low-temperature crystal structures of orthoclase and sanidine. Neues Jahrbuch für Mineralogie, Abhandlungen: 171: 199-213.

Mineralien Welt (1999): 10(6): 40-44.

Ginibre, C., Wörner, G., and Kronz, A. (2004) Structure and dynamics of the Laacher See magma chamber (Eifel, Germany) from major and trace element zoning in sanidine: a cathodoluminescence and electron microprobe study. Journal of Petrology: 45: 2197-2224.

Internet Links for Sanidine

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    Localities for Sanidine

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