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Slawsonite

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Sarusaka, Kagami, Kochi Prefecture, Shikoku Island, Japan
© 2008, J. Weissman

Formula:
(Sr,Ca)[Al
 
2
Si
 
2
O
 
8
]
System:MonoclinicColour:Colourless, gray
Hardness:5½ - 6½
Name:Named after Chester Baker Slawson, Professor of Mineralogy.


Feldspar Group.

Classification of Slawsonite

IMA status:Approved
Strunz 8th edition ID:8/J.06-80
Nickel-Strunz 10th (pending) edition ID:9.FA.50

9 : SILICATES (Germanates)
F : Tektosilicates without zeolitic H2O
A : Tektosilicates without additional non-tetrahedral anions
Dana 8th edition ID:76.1.5.2

76 : TECTOSILICATES Al-Si Framework
1 : Al-Si Framework with Al-Si frameworks
Hey's CIM Ref.:16.12.2

16 : Silicates Containing Aluminum and other Metals
12 : Aluminosilicates of Sr, Ba and Zn
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Type Occurrence of Slawsonite

Type Locality:Martin Bridge formation, Wallowa Co., Oregon, USA
Year of Discovery:1977

Physical Properties of Slawsonite

Lustre:Vitreous
Diaphaneity (Transparency):Transparent
Colour:Colourless, gray
Hardness (Mohs):5½ - 6½

Crystallography of Slawsonite

Crystal System:Monoclinic
Cell Parameters:a = 8.89Å, b = 9.35Å, c = 8.33Å
Ratio:a:b:c = 0.951 : 1 : 0.891
Unit Cell Volume:V 0.00 ų (Calculated from Unit Cell)

Optical Data of Slawsonite

Type:Biaxial (-)
RI values: nα = 1.570 - 1.573 nβ = 1.581 - 1.582 nγ = 1.585 - 1.586
2V:Measured: 55° to 82°, Calculated: 60° to 66°
Maximum Birefringence:δ = 0.015

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

Chemical Properties of Slawsonite

Formula:
(Sr,Ca)[Al
 
2
Si
 
2
O
 
8
]
Essential elements:Al, O, Si, Sr
All elements listed in formula:Al, Ca, O, Si, Sr
Common Impurities:Ti,Fe,Mg,Na,K,H2O

Relationship of Slawsonite to other Species

Related Minerals - Nickel-Strunz Grouping):
9.FA.IMA2007-049
NaAlSi
 
3
O
 
8
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.30Sanidine
K[AlSi
 
3
O
 
8
]
9.FA.30Rubicline
(Rb,K)[AlSi
 
3
O
 
8
]
9.FA.30Kokchetavite
KAlSi
 
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.35Lingunite
(Na,Ca)AlSi
 
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.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
Ca[BSiO
 
4
]
 
2
9.FA.65Maleevite
BaB
 
2
Si
 
2
O
 
8
9.FA.65Pekovite
SrB
 
2
Si
 
2
O
 
8
Related Minerals - Hey's Index Grouping:
16.12.1Stronalsite
SrNa
 
2
[Al
 
2
Si
 
2
O
 
8
]
 
2
16.12.3Brewsterite
16.12.4Celsian
Ba[Al
 
2
Si
 
2
O
 
8
]
16.12.5Paracelsian
Ba[Al
 
2
Si
 
2
O
 
8
]
16.12.6Cymrite
BaAl
 
2
Si
 
2
(O,OH)
 
8
·H
 
2
O
16.12.7Edingtonite
Ba[Al
 
2
Si
 
3
O
 
10
] · 4H
 
2
O
16.12.8Banalsite
BaNa
 
2
[Al
 
2
Si
 
2
O
 
8
]
 
2
16.12.9Harmotome
(Ba
 
0.5
,Ca
 
0.5
,K,Na)
 
5
[Al
 
5
Si
 
11
O
 
32
] ·12H
 
2
O
16.12.10Hyalophane
(K,Ba)[Al(Si,Al)Si
 
2
O
 
8
]
16.12.11Balipholite
BaLiMg
 
2
Al
 
3
[(OH)
 
4
|Si
 
2
O
 
6
]
 
2
16.12.12Armenite
BaCa
 
2
Al
 
6
Si
 
9
O
 
30
·2H
 
2
O
16.12.13Wellsite
(Ba,Ca,K
 
2
)Al
 
2
Si
 
6
O
 
16
·6H
 
2
O
16.12.14Merlinoite
(K,Na)
 
5
(Ca,Ba)
 
2
Al
 
9
Si
 
23
O
 
64
·23H
 
2
O
16.12.15Anandite
(Ba,K)(Fe
2+
 
,Mg)
 
3
[(O,OH)
 
2
|(Si,Al,Fe)
 
4
O
 
10
]
16.12.16Fraipontite
(Zn,Al)
 
3
[(OH)
 
4
|(Si,Al)
 
2
O
 
5
]
16.12.17Sauconite
Na
 
0.3
Zn
 
3
(Si,Al)
 
4
O
 
10
(OH)
 
2
·4H
 
2
O
16.12.18Minehillite
(K,Na)
 
2-3
Ca
 
28
Zn
 
4
Al
 
4
Si
 
40
O
 
112
(OH)
 
16
16.12.19Hendricksite
K(Zn,Mg,Mn
2+
 
)
 
3
[(OH)
 
2
|AlSi
 
3
O
 
10
]
16.12.20Baileychlore
(Zn,Fe,Al,Mg)
 
6
(Si,Al)
 
4
O
 
10
(OH)
 
8

Other Names for Slawsonite

Synonyms:
IMA1967-026
German names:
Slawsonit
Russian names:
Слаусонит
Spanish names:
Slawsonita

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 Slawsonite

Reference List:American Mineralogist (1977): 62: 31-35.

American Mineralogist (1987): 72: 225-226.

Zeitschrift für Kristallographie: 210: 741-745.

Internet Links for Slawsonite

Search Engines:
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  • Raman and XRD data at RRUFF project
  • American Mineralogist Crystal Structure Database
  • Search for Slawsonite in the Natural History Museum (London) online catalogue
  • Slawsonite details from Handbook of Mineralogy (PDF)
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    Localities for Slawsonite

    (TL) indicates type locality. ? indicates mineral may be doubtful at this locality. All other localities listed without reference should be considered as uncertain and unproven until references can be found.
    Japan
     
    • Honshu Island
      • Chubu Region
        • Niigata Prefecture
    		Miyajima, H. et al., abstract J038-003, in www-jm.eps.s.u-tokyo.ac.jp/ 2002cd-rom/pdf/j038/j038-003_e.pdf
    • Shikoku Island
      • Kochi Prefecture
        • Kagami
    		Handbook of Mineralogy, (c) 2001.
        • Kochi City
    USA
     
    • Oregon
      • Wallowa Co.
    		Am Min 62:31-35
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