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Gerstleyite

Formula:
Na
 
2
(Sb,As)
 
8
S
 
13
·2H
 
2
O
System:MonoclinicColour:Cinnabar red, darkening ...
Lustre:Sub-AdamantineHardness:
Name:Named after James Mack Gerstley (1907- ), president of the Pacific Coast Borax Co.


As as red spherules with fibrous to platy structue up to 2.5 cm in clay with borates. This was the first known sodium sulfosalt.

Classification of Gerstleyite

IMA status:Valid - first described prior to 1959 (pre-IMA) - "Grandfathered" 1956
Strunz 8th edition ID:2/F.10-10
Nickel-Strunz 10th (pending) edition ID:2.HE.05

2 : SULFIDES and SULFOSALTS (sulfides, selenides, tellurides; arsenides, antimonides, bismuthides; sulfarsenites, sulfantimonites, sulfbismuthites, etc.)
H : Sulfosalts of SnS archetype
E : With alkalies, H2O
Dana 8th edition ID:3.8.8.1

3 : SULFOSALTS
8 : 1 < ø < 2
Hey's CIM Ref.:5.0.1

5 : Sulphosalts - Sulpharsenites and Sulphobismuthites (those containing Sn, Ge,or V are in Section 6)
0 : Sulpharsenites etc. of the alkali metals
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Type Occurrence of Gerstleyite

Type Locality:Baker mine, U.S. Borax Mine, Boron, Kramer District, Kern Co., California, USA
Place of Conservation of Type Material:Smithsonian, Harvard
Year of Discovery:1956
Geological Setting of type material:Low temperature Borate evaporite

Occurrences of Gerstleyite

Geological Setting:As above

Physical Properties of Gerstleyite

Lustre:Sub-Adamantine
Diaphaneity (Transparency):Translucent
Colour:Cinnabar red, darkening on exposure
Streak:Bright cinnabar red
Hardness (Mohs):
Hardness Data:Measured
Tenacity:Brittle
Cleavage:Perfect
Perfect on 010 and 100,Poor on 001
Fracture:None observed
Density (measured):3.62 g/cm3
Density (calculated):3.723 g/cm3

Crystallography of Gerstleyite

Crystal System:Monoclinic
Class (H-M):m - Domatic
Space Group:Bm (B1 1m) [Cm] {C1m1}
Cell Parameters:a = 9.911Å, b = 23.05Å, c = 7.097Å
α = 90°, β = 127.85°, γ = 90°
Ratio:a:b:c = 0.43 : 1 : 0.308
Unit Cell Volume:V 1,280.21 ų (Calculated from Unit Cell)
Z:2
Morphology:Fibrous and platy
X-Ray Powder Diffraction:
d-spacingIntensity
11.85 (100)
3.05 (90)
5.64 (70)
4.03 (70)
2.81 (50)
2.739 (40)
Comments:From type material at Baker Mine, Kern Co., Ca., USA

Optical Data of Gerstleyite

Type:Biaxial
Dispersion:r < v extreme
Pleochroism:Weak
Comments:X= salmon red, Y=Z= deep blood red

Chemical Properties of Gerstleyite

Formula:
Na
 
2
(Sb,As)
 
8
S
 
13
·2H
 
2
O
Essential elements:As, H, Na, O, S, Sb
All elements listed in formula:As, H, Na, O, S, Sb
Analyical Data:The analysis is not very good totalling 92%. The structure determination must have used better
             1         2        3
Na         4.28      4.65      3.29
Li         0.135     0.15
Sb        47.80     51.91     55.74
As         7.38      8.02      8.57
S         27.01     29.33     29.82
H^2O       5.47      5.94      2.58
gangue     n.d.
Total     92.07    100.00    100.00
1) Type material 2) same corrected to 100% 3)Na^2(Sb,As)^8S^13.2H^2O
Common Impurities:Li

Other Names for Gerstleyite

Other Languages:
German:Gerstleyit
Russian:Герслиит
Spanish:Gerstleyita

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.
Industrial Uses:none

References for Gerstleyite

Reference List:Frondel,C. and Morgan,V. (1956) Inderite and Gerstleyite From The Kramer borate district, Kern Co. California, American Mineralogist: 41: 839-843.

Nakai,I. and Appleman, D.E. (1981) The crystal structure of Gerstleyite Na^2(Sb.As)^8S^13.2H^2O: The first sulfosalt mineral of sodium. Chem. Lett: 1981(10): 1327-1330.

Geological Society of America, Program with Abstracts: 11(7): 485.

Chemical Abstracts: 95: 195617y.


Handbook vol 1, pg 181

Articles/Blogs about Gerstleyite

Internet Links for Gerstleyite

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    Localities for Gerstleyite

    The 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.
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    (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.
    USA
     
    • California
      • Kern Co.
        • Kramer District
    www.mineralsocal.org
            • U.S. Borax Mine
    American Mineralogist 41 (1956), 839-843
    collected by Rock Currier
    Cal Div of Mines & Geology "Mineral Information Service" V. 22 N. 9 Sept 1969
    Mineral and/or Locality
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