Kampfite

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Kampfite
Traskite (brown)-Kampfite (bluish).jpg
Traskite (brown) and Kampfite (bluish), from Big Creek, Fresno County, California, United States of America
General
CategoryPhyllosilicate
Formula
(repeating unit)
Ba
12
(Si
11
Al
5
)O
31
(CO
3
)
8
Cl
5
Strunz classification9.EG.20
Crystal systemMonoclinic
Crystal classDomatic (m)
(same H-M symbol)
Space groupCc
Unit cella = 31.2329, b = 5.2398
c = 9.0966 [Å]; β = 106.933°; Z = 1
Identification
ColorLight blue gray
Crystal habitIrregular grains or anhedral crystal inclusions
CleavageGood on {001}
FractureUneven
TenacityBrittle
Mohs scale hardness3
LusterVitreous
StreakWhite
DiaphaneityTranslucent
Specific gravity3.45
Optical propertiesUniaxial - (strongly pseudohexagonal)
Refractive indexnω = 1.642 nε = 1.594
Birefringenceδ = 0.048
References[1][2]

Kampfite is a rare barium silicatecarbonatehalide mineral with the chemical formula Ba
12
(Si
11
Al
5
)O
31
(CO
3
)
8
Cl
5
. Discovered in 1964 and described in 2001, it is named after Anthony R. Kampf. The mineral is known only from Fresno County, California.

Description[]

Kampfite is translucent and light blue-gray in color. Specimens occur as irregular masses up to 1 cm (0.39 in) in size.[3]

Composition and structure[]

When first described, the formula was identified as Ba
6
[(Si,Al)O
2
]
8
(CO
3
)
2
Cl
2
(Cl,H
2
O)
2
.[4] Subsequent work on analyzing the crystal structure led to a revised formula of Ba
12
(Si
11
Al
5
)O
31
(CO
3
)
8
Cl
5
. The structural H
2
O
noted in the original description was not found in the later work.[5]

The structure consists of double layers of tetrahedra connected by barium-containing polyhedra. It is this layering which causes kampfite's one perfect cleavage.[6][7] Kampfite shares chemical and structural similarities with cymrite.[6] As of 2007, it is the only known barium silicate carbonate aside from .[5]

Occurrence[]

Kampfite has been found in association with celsian, , macdonaldite, pyrrhotite, , , and witherite.[3] The mineral is known only from locations in Fresno County, California.[1][3] Kampfite is found in quartz-rich regions of sanbornite rocks[4] within gneiss which has undergone contact metamorphism associated with an adjacent granodiorite intrusive.[3]

History[]

The mineral discovered in 1964 by Robert Walstrom from the Esquire #1 claim of the Rush Creek deposit in eastern Fresno County.[8] It was described in 2001 in The Canadian Mineralogist.[4] The mineral was named kampfite in honor of Anthony Robert Kampf (1948–), curator of the Los Angeles County Museum of Natural History, for his crystallography work on new and rare minerals.[8]

Co-type specimens are held by the University of British Columbia and the Geological Survey of Canada.[9]

References[]

  1. ^ Jump up to: a b Kampfite on Mindat.org
  2. ^ Kampfite data on Webmin
  3. ^ Jump up to: a b c d Anthony, John W.; Bideaux, Richard A.; Bladh, Kenneth W.; Nichols, Monte C. (eds.). "Kampfite" (PDF). Handbook of Mineralogy. Chantilly, VA: Mineralogical Society of America.
  4. ^ Jump up to: a b c Basciano et al. 2001, p. 1053.
  5. ^ Jump up to: a b Basciano & Groat 2007, p. 942.
  6. ^ Jump up to: a b Basciano & Groat 2007, p. 935.
  7. ^ Basciano & Groat 2007, p. 940.
  8. ^ Jump up to: a b Basciano et al. 2001, p. 1054.
  9. ^ Basciano et al. 2001, pp. 1054–1055.

Bibliography[]

External links[]

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