Kampfit

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Kampfit
Traskite (brown) -Kampfite (bluish) .jpg
Traskit (brown) with Kampfit (bluish)
General and classification
other names

IMA 2000-003

chemical formula Ba 12 (Si 11 Al 5 ) O 31 (CO 3 ) 8 Cl 5
Mineral class
(and possibly department) 		Silicates and Germanates
System no. to Strunz
and to Dana 		9.EG.20 ( 8th edition : VIII / H.38)
May 78, 10.01
Crystallographic Data
Crystal system monoclinic
Crystal class ; symbol monoclinic; m
Space group Cc (No. 9)Template: room group / 9
Lattice parameters a  = 31.2329 (7)  Å ; b  = 5.2398 (1) Å; c  = 9.0966 (3) Å
β  = 106.933 (2) °
Formula units Z  = 1
Physical Properties
Mohs hardness 3
Density (g / cm 3 ) calculated: 3.51
Cleavage completely after {001}
colour light blue-gray, greener
Line color White
transparency translucent
shine Glass gloss
Crystal optics
Refractive indices n ω  = 1.642
n ε  = 1.594
Birefringence δ = 0.048
Optical character uniaxial negative

The mineral kampfite is a very rarely occurring sheet silicate with the chemical composition Ba 12 (Si 11 Al 5 ) O 31 (CO 3 ) 8 Cl 5 . It crystallizes in the monoclinic crystal system and has so far only been found in the form of massive aggregates of light blue-gray or greenish color.

Etymology and history

Kampfit was discovered in 1964 in the “Esquire No. 1 ”on Rush Creek in Fresno County (California) by one of the first-time descriptors. Laurel C. Basciano, Lee A. Groat, Andrew C. Roberts, Joel D. Grice, Gai E. Dunning, Eugene E. Foord, Ingrid M. Kjarsgaard and Robert E. Walstrom named the mineral after Anthony Robert Kampf (* 1948) , the curator and section head of the Mineral Collection of the Natural History Museum of Los Angeles County , to recognize his many significant contributions to the crystallographic study of new and rare minerals.

The composition given in the original description Ba 6 [(Si, Al) O 2 ] 8 (CO 3 ) 2 Cl 2 (Cl, H 2 O) 2 and the lattice parameters determined on the basis of a hexagonal unit cell had to be re-analyzed in 2007 by Laurel C. Basciano and Lee A. Groat are corrected.

classification

In the meanwhile outdated, but still in use 8th edition of the mineral classification according to Strunz , the kampfite belonged to the mineral class of "silicates and germanates" and there to the department of "phyllosilicates", where together with cymrite , delhayelite , hydrodelhayelite , lourenswalsite , Macdonaldit , Monteregianit- (Y) , Rhodesit , Tienshanit and Wickenburgit the unnamed group VIII / H.38 formed.

The 9th edition of Strunz's mineral systematics, which has been in effect since 2001 and is used by the International Mineralogical Association (IMA), also assigns kampfite to the class of “silicates and germanates” and there to the “phyllosilicates” section. This department is, however, further subdivided according to the crystal structure, so that the mineral can be found according to its structure in the subdivision "Double networks with 6-membered rings", where it is the only member of the unnamed group 9.EG.20 .

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns Kampfite to the class of "silicates and Germanates", but there it is in the "unclassified silicate minerals" category. Here he is the only member of the unnamed group May 78, 2010 within the sub-section “ Unclassified Silicates: Possible Layered Silicates ”.

Education and Locations

Kampfite forms in the form of irregular masses up to about 10 millimeters in size, as inclusions in quartz-rich areas of rocks containing sanbornite. Accompanying minerals include celsian , fresnoite , macdonaldite , pyrrhotite , titanium taramellite , traskite and witherite .

In addition to its type locality , the “Esquire No. 1 "at Rush Creek, the mineral was previously (as of 2012) in the pit field" Esquire No. 7 “at nearby Big Creek (Fresno County, California).

Crystal structure

Kampfite crystallizes monoclinically in the space group Cc (space group no. 9) with the lattice parameters a  = 31.2329 (7)  Å ; b  = 5.2398 (1) Å; c  = 9.0966 (3) Å and β = 106.933 (2) ° as well as one formula unit per unit cell . Template: room group / 9

See also

literature

  • Laurel C. Basciano, Lee A. Groat, Andrew C. Roberts, Joel D. Grice, Gai E. Dunning, Eugene E. Foord, Ingrid M. Kjarsgaard, Robert E. Walstrom: Kampfite, a new barium silicate carbonate mineral species from Fresno County, California , in: The Canadian Mineralogist , Volume 39 (2001), pp. 1053-1058 ( PDF 297.6 kB )

Web links

Commons : Kampfite  - Collection of images, videos and audio files

Individual evidence

  1. ↑ a b c d e f Laurel C. Basciano, Lee A. Groat: The crystal structure of Kampfite , in: The Canadian Mineralogist (2007), Vol. 45 No. 4, pp. 935-943, doi : 10.2113 / gscanmin .45.4.935 ( PDF )
  2. ↑ Webmineral - Kampfite
  3. ↑ a b c d Basciano et al .: Kampfite, a new barium silicate carbonate mineral species from Fresno County, California (see literature)
  4. ↑ a b c Mindat - Kampfite