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Cahnite

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Formula:
Ca2[B(OH)4](AsO4)
System:
Tetragonal
Colour:
Colorless to white, also ...
Hardness:
3
Name:
Named in 1921 by Charles Palache, but not described until 1927 by Charles Palache and Lawson Henry Bauer in honor of Mr. Lazard Cahn [May 23, 1865 Saint Joseph, Missouri, USA - May 22, 1940 Colorado S[rings, Colorado, USA] morphological crystallographer, mineral collector and mineral dealer, who first recognized the material.
Related to Moydite-(Y).

Classification of Cahnite

Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
6.AC.70

6 : BORATES
A : Monoborates
C : B(O,OH)4, without and with additional anions; 1(T), 1(T)+OH, etc
43.4.4.1

43 : COMPOUND PHOSPHATES, ETC.
4 : Anhydrous Compound Phosphates, etc·, Containing Hydroxyl or Halogen
10.2.2

10 : Borates with other anions
2 : Borates with phosphate or arsenate
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Type Occurrence of Cahnite

Year of Discovery:
1921
Geological Setting of Type Material:
Cavities in manganaxinite veinlets traversing Precambrian metamorphosed Zn-Mn-Fe orebody.
Associated Minerals at Type Locality:

Occurrences of Cahnite

Geological Setting:
cavities in boron-bearing and arsenate-bearing vugs in basalt, boron-bearing and arsenate-bearing hydrothermal veins

Physical Properties of Cahnite

Vitreous, Sub-Vitreous, Resinous
Diaphaneity (Transparency):
Transparent, Translucent
Colour:
Colorless to white, also golden brown; colourless in transmitted light.
Streak:
White
Hardness (Mohs):
3
Tenacity:
Brittle
Cleavage:
Perfect
On {110}
Fracture:
Irregular/Uneven, Sub-Conchoidal
Density:
3.156 g/cm3 (Measured)    3.22 g/cm3 (Calculated)

Crystallography of Cahnite

Crystal System:
Tetragonal
Class (H-M):
4 - Disphenoidal
Space Group:
P4
Cell Parameters:
a = 7.09Å, c = 6.19Å
Ratio:
a:c = 1 : 0.873
Unit Cell Volume:
V 311.16 ų (Calculated from Unit Cell)
Z:
2
Morphology:
Single untwinned crystals rare, pseudo-tetrahedral habit.
Twinning:
Almost universal on {110}, with the individuals interpenetrating symmetrically. When the sphenoid faces are well-developed, the twins have a characteristic cruciform appearance.
X-Ray Powder Diffraction Data:
d-spacingIntensity
5.02 (20)
4.67 (20)
3.56 (100)
2.833 (19)
2.640 (48)
2.336 (17)
1.818 (52)

Optical Data of Cahnite

Type:
Uniaxial (+)
RI values:
nω = 1.655 - 1.662 nε = 1.656 - 1.663
Birefringence:
0.001
Max Birefringence:
δ = 0.001
Image shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:
Moderate
Dispersion:
Strong.
Pleochroism:
Non-pleochroic
Comments:
Exhibits abnormal interference colours.

Chemical Properties of Cahnite

Formula:
Ca2[B(OH)4](AsO4)
Essential elements:
All elements listed in formula:

Relationship of Cahnite to other Species

6.AC.05SinhaliteMgAl(BO4)
6.AC.10PseudosinhaliteMg2Al3(BO3)2(OH)O3
6.AC.15Behierite(Ta5+,Nb5+)(BO4)
6.AC.15Schiavinatoite(Nb,Ta)(BO4)
6.AC.20FroloviteCa[B(OH)4]2
6.AC.25HexahydroboriteCa[B(OH)4]2 · 6H2O
6.AC.30HenmiliteCa2Cu[B(OH)4]2(OH)4
6.AC.35BandyliteCu[B(OH)4]Cl
6.AC.40TeepleiteNa2[B(OH)4]Cl
6.AC.45Moydite-(Y)Y[B(OH)4](CO3)
6.AC.50CarboboriteCa2Mg[B(OH)4]2(CO3)2 · 4H2O
6.AC.55SulfoboriteMg3[B(OH)4]2(SO4)(OH,F)2
6.AC.60LüneburgiteMg3[B2(OH)6](PO4)2 · 6H2O
6.AC.65SeamaniteMn32+[B(OH)4](PO4)(OH)2
10.2.1LüneburgiteMg3[B2(OH)6](PO4)2 · 6H2O
10.2.3TeruggiteCa4Mg[AsO4|B6O7(OH)6]2 · 12H2O
10.2.4SeamaniteMn32+[B(OH)4](PO4)(OH)2

Other Names for Cahnite

Name in Other Languages:
German:Cahnit
Japanese:カーン石
Russian:Канит
Simplified Chinese:砷硼钙石
水砷硼钙石
Spanish:Cahnita

Other Information

Fluoresces moderate creamy white in SW UV (Franklin).
Other Information:
Readily soluble in dilute HCl.
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 Cahnite

Reference List:
Palache, C. and Bauer, L. (1927) American Mineralogist: 12: 149-153.

Palache, C. (1941) American Mineralogist: 26: 429.

Palache, C., Berman, H., & Frondel, C. (1951), The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana, Yale University 1837-1892, Volume II. John Wiley and Sons, Inc., New York, 7th edition, revised and enlarged: 386-387.

American Mineralogist (1961): 46: 1077-1085.

Grew, E.S., and Anovitz, L.M. (1996) BORON: Mineralogy, Petrology and Geochemistry, second edition, as revised (2002).

Internet Links for Cahnite

Localities for Cahnite

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.
(TL) indicates type locality for a valid mineral species. (FRL) indicates first recorded locality for everything else. ? 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.
Brazil
 
  • Goiás
Orris, G.J., and Grauch, R.I. (2002): USGS Open-File Report 02-189.
Chile
 
  • Antofagasta Region
    • El Loa Province
TESIS PARA OPTAR AL GRADO DE MAGÍSTER EN CIENCIAS, MENCIÓN GEOLOGÍA MEMORIA PARA OPTAR AL TÍTULO DE GEÓLOGO CONSTANZA BEATRIZ NICOLAU DEL ROURE EYLERTS, 2013
China
 
  • Inner Mongolia Autonomous Region
    • Ulanhad League (Chifeng Prefecture)
      • Hexigten Banner (Keshiketeng Co.)
        • Huanggang Fe-Sn deposit (Huanggangliang Mine; Huanggang Mine)
Ottens, B. and G. Neumeier (2012) The Huanggang Mine, Inner Mongolia, China. Mineralogical Record 43:529-563
      • Linxi Co.
        • Linxi
Ottens, B. & Bin, J. (2014): Seltene Boratmineralien aus der Inneren Mongolei, China. Lapis, 39 (7/8), 66-68.
Italy
 
  • Latium
    • Rome Province
      • Rome
        • Valleranello
Stoppani F.S. & Curti E. (1982): I minerali del Lazio, Olimpia, Ed., 266-267.
Japan
 
  • Honshu Island
    • Chugoku Region
      • Okayama Prefecture
        • Takahashi City
          • Bicchu-cho (Bitchu-cho)
            • Fuka
Shiraga et al (2002), Jourmal of Mineralogical and Petrological Sciences 97,70-73(2002)
Namibia
 
  • Otjozondjupa Region
    • Grootfontein District
      • Kombat
Dunn, P.J. (1991), Rare minerals of the Kombat Mine, Mineralogical Record: 22(6): 421-425.
Norway
 
  • Aust-Agder
    • Arendal
      • Arendal Iron Mines
        • Øyestad
Bugge, J.A.W. (1951); Minerals from the skarn iron ore deposits at Arendal, Norway. I. Cahnite from Klodeborg mine. Det Kongelige Norske Videnskabers Selskab Skrifter, Forhandliger 24:79-81
Russia
 
  • Eastern-Siberian Region
    • Transbaikalia (Zabaykalye)
      • Buriatia Republic (Buryatia)
        • Vitim Plateau
Doklady Acad. Nauk SSSR 166,695-697(1966)
Turkey
 
  • Aegean Region
    • Kütahya Province
      • Emet
        • Emet Borate deposit
American Mineralogist; April 1979; v. 64; no. 3-4; p. 362-366
C.Helvaci & R.N.Alonso (2000) Borate Deposits of Turkey and Argentina; A Summary and Geological Comparison. Turkish Journal of Earth Sciences, 9, 1-27(2000); American Mineralogist; April 1979; v. 64; no. 3-4; p. 362-366
USA (TL)
 
  • New Jersey
    • Sussex Co.
      • Franklin Mining District
        • Franklin
Palache, C. (1935) American Mineralogist: 26: 126; Palache, C., Berman, H., & Frondel, C. (1951), The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana, Yale University 1837-1892, Volume II: 387; Dunn, P.J. (1995): Part5: 660-663.
Mineral and/or Locality  
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