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Sanidine

Big Photo

Agua de Pau volcano (Fogo volcano), San Miguel Island, Azores District, Portugal
© GiovanniFraccaro

Show Sanidine Photos (66)
Formula:
K[AlSi
 
3
O
 
8
]
System:MonoclinicColour:Colourless, white, grey, ...
Lustre:VitreousHardness:6
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.

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:Carlbad - common
Baveno, Manebach - rarer
Comment: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:
K[AlSi
 
3
O
 
8
]
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

Related to:
  • Feldspar Group
    • Related Minerals - Nickel-Strunz Grouping):

    - +
    9.FA.05Kaliophilite
    K[AlSiO
     
    4
    		]
    9.FA.05Kalsilite
    K[AlSiO
     
    4
    		]
    9.FA.05Nepheline
    (Na,K)[AlSiO
     
    4
    		]
    9.FA.05Panunzite
    (Na,K)[AlSiO
     
    4
    		]
    9.FA.05Trikalsilite
    (Na,K)[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
    Ba[Al
     
    2
    		Si
     
    2
    		O
     
    8
    		]
    9.FA.30Hyalophane
    (K,Ba)[Al(Si,Al)Si
     
    2
    		O
     
    8
    		]
    9.FA.30Microcline
    K[AlSi
     
    3
    		O
     
    8
    		]
    9.FA.30Orthoclase
    K[AlSi
     
    3
    		O
     
    8
    		]
    9.FA.30Rubicline
    (Rb,K)[AlSi
     
    3
    		O
     
    8
    		]
    9.FA.30Monalbite
    Na[AlSi
     
    3
    		O
     
    8
    		]
    9.FA.35Albite
    Na[AlSi
     
    3
    		O
     
    8
    		]
    9.FA.35Andesine
    (Na,Ca)[Al(Si,Al)Si
     
    2
    		O
     
    8
    		]
    9.FA.35Anorthite
    Ca[Al
     
    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
    Ba[Al
     
    2
    		Si
     
    2
    		O
     
    8
    		]
    9.FA.45Svyatoslavite
    Ca[Al
     
    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
    K[AlSiO
     
    4
    		]
    16.3.3Kalsilite
    K[AlSiO
     
    4
    		]
    16.3.4Leucite
    KAlSi
     
    2
    		O
     
    6
    16.3.5Microcline
    K[AlSi
     
    3
    		O
     
    8
    		]
    16.3.6Orthoclase
    K[AlSi
     
    3
    		O
     
    8
    		]
    16.3.8Muscovite
    KAl
     
    2
    		[(OH)
     
    2
    		|AlSi
     
    3
    		O
     
    10
    		]

    Other Names for Sanidine

    Synonyms:
    Glassy FeldsparGränzeriteRhyacoliteRhyakolithRiacolite
    Other Languages:
    Finnish:Sanidiini
    German:Sanidin
    Glasiger Feldspath
    Gränzerit
    Rhyacolit
    Riacolit
    Hebrew:סנידין
    Italian:Sanidino
    Japanese:サニディン
    Russian:Санидин
    Spanish:Gränzerita
    Rhyacolita
    Riacolita
    Varieties:
    AzuliciteBarium-Sanidine

    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 Sanidine: die Ausnahmerolle der Eifelsanidin-Megacrystal. 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 cathodluminescence and electron microprobe study. Journal of Petrology: 45: 2197-2224.

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    Localities for Sanidine

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