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Cahnite

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Franklin Mine, Franklin, Franklin Mining District, Sussex Co., New Jersey, USA
© Rob Lavinsky

Show Cahnite Photos (6)
Formula:
Ca
 
2
[AsO
 
4
|B(OH)
 
4
]
System:TetragonalColour:Colourless to white; ...
Hardness:3
Name:After Mr. Lazard Cahn (1865-1940) mineral collector and dealer, who first recognized the material.


Moydite-Cahnite Group

Classification of Cahnite

IMA status:Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
Strunz 8th edition ID:5/G.08-30
Strunz 9th edition ID:6.AC.25
Nickel-Strunz 10th (pending) edition ID:6.AC.70

6 : BORATES
A : Monoborates
C : B(O,OH)4, without and with additional anions; 1(T), 1(T)+OH, etc
Dana 8th edition ID:43.4.4.1

43 : COMPOUND PHOSPHATES, ETC.
4 : Anhydrous Compound Phosphates, etc·, Containing Hydroxyl or Halogen
Hey's CIM Ref.:10.2.2

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

Type Locality:Franklin Mine, Franklin, Franklin Mining District, Sussex Co., New Jersey, USA
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:
WillemiteRhodonitePyrochroiteHedyphaneDatolite
Baryte

Physical Properties of Cahnite

Lustre:Vitreous
Diaphaneity (Transparency):Transparent
Colour:Colourless to white; colourless in transmitted light.
Hardness (Mohs):3
Tenacity:Brittle
Cleavage:Perfect
On {110}
Density (measured):3.156 g/cm3

Crystallography of Cahnite

Crystal System:Tetragonal
Class (H-M):4 - Disphenoidal
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)
Morphology:Single untwinned crystals rare, pseudo-tetragonal 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.

Optical Data of Cahnite

Type:Uniaxial (+)
RI values: nω = 1.662 nε = 1.663
Maximum Birefringence:δ = 0.001

Chart shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:Moderate
Dispersion:Strong.
Comments:Exhibits abnormal interference colours.

Chemical Properties of Cahnite

Formula:
Ca
 
2
[AsO
 
4
|B(OH)
 
4
]
Essential elements:As, B, Ca, H, O
All elements listed in formula:As, B, Ca, H, O

Relationship of Cahnite to other Species

Related Minerals - Nickel-Strunz Grouping):
6.AC.05Sinhalite
MgAl[O|BO
 
3
]
6.AC.10Pseudosinhalite
Mg
 
2
Al
 
3
[O
 
3
|OH|(BO
 
3
)
 
2
]
6.AC.15Behierite
(Ta
5+
 
,Nb
5+
 
)[O|BO
 
3
]
6.AC.15Schiavinatoite
(Nb,Ta)BO
 
4
6.AC.20Frolovite
Ca[B(OH)
 
4
]
 
2
6.AC.25Hexahydroborite
Ca[B(OH)
 
4
]
 
2
 · 6H
 
2
O
6.AC.30Henmilite
Ca
 
2
Cu[(OH)
 
2
|B(OH)
 
4
]
 
2
6.AC.35Bandylite
Cu[Cl|B(OH)
 
4
]
6.AC.40Teepleite
Na
 
2
[Cl|B(OH)
 
4
]
6.AC.45Moydite-(Y)
Y[CO
 
3
|B(OH)
 
4
]
6.AC.50Carboborite
Ca
 
2
Mg[CO
 
3
|B(OH)
 
4
]
 
2
 · 4H
 
2
O
6.AC.55Sulfoborite
Mg
 
3
[(OH,F)
 
2
|SO
 
4
|{B(OH)
 
4
}
 
2
]
6.AC.60Lüneburgite
Mg
 
3
B
 
2
(PO
 
4
)
 
2
(OH)
 
6
·6H
 
2
O
6.AC.65Seamanite
Mn
2+
3
[(OH)
 
2
|PO
 
4
|B(OH)
 
4
]
Related Minerals - Hey's Index Grouping:
10.2.1Lüneburgite
Mg
 
3
B
 
2
(PO
 
4
)
 
2
(OH)
 
6
·6H
 
2
O
10.2.3Teruggite
Ca
 
4
Mg[AsO
 
4
|B
 
6
O
 
7
(OH)
 
6
]
 
2
 · 12H
 
2
O
10.2.4Seamanite
Mn
2+
3
[(OH)
 
2
|PO
 
4
|B(OH)
 
4
]

Other Names for Cahnite

Synonyms:
Calcium Edingtonite
German names:
Cahnit
Japanese names:
カーン石
Russian names:
Канит
Spanish names:
Cahnita

Other Information

Other Information:Readily soluble in dilute HCl.
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 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

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    Localities for Cahnite

    Hide Locality List
    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.
    Brazil
     
    • Central-West Region
      • Goiás
    		Orris, G.J., and Grauch, R.I. (2002): USGS Open-File Report 02-189.
    Italy
     
    • Latium
      • Rome Province
        • Alban Hills
    		Mineralogical. Magazine, 32, 666-668
        • Rome
          • Vallerano
    Japan
     
    • Honshu Island
      • Chugoku Region
        • Okayama Prefecture
          • Takahashi
            • Bitchu-cho (Bicchu-cho)
    		Shiraga et al (2001) Koubutsu-Gakkai Kou'en-Youshi (Abstracts of the Meeting Of the Mineralogical Society of Japan), 115.
    Namibia
     
    • Otjozondjupa Region
      • Grootfontein District
        • Kombat
    		Mineralogical Record: 22: 421.
    Norway
     
    • Aust-Agder
      • Arendal
        • Arendal Iron Mines
    		Bugge (1951); Neumann (1985, pp. 103-104).
    Turkey
     
    • Aegean Region
      • Kütahya Province
    		CAHIT HELVACI & RICARDO N. ALONSO (2000) Borate Deposits of Turkey and Argentina; A Summary and Geological Comparison. Turkish Journal of Earth Sciences, Vol. 9, 2000, pp. 1-27
    USA
     
    • 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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