Kampfite is a rare barium silicate–

carbonate A carbonate is a salt of carbonic acid (H2CO3), characterized by the presence of the carbonate ion, a polyatomic ion with the formula . The word ''carbonate'' may also refer to a carbonate ester, an organic compound containing the carbonate ...

– halide mineral with the chemical formula . Discovered in 1964 and described in 2001, it is named after Anthony R. Kampf. The mineral is known only from

Fresno County, California Fresno County (), officially the County of Fresno, is a county located in the central portion of the U.S. state of California. As of the 2020 Census, the population was 1,008,654. The county seat is Fresno, the fifth-most populous city in Ca ...

Description

Kampfite is translucent and light blue-gray in color. Specimens occur as irregular masses up to in size.

Composition and structure

When first described, the formula was identified as . Subsequent work on analyzing the crystal structure led to a revised formula of . The structural noted in the original description was not found in the later work. The structure consists of double layers of tetrahedra connected by barium-containing polyhedra. It is this layering which causes kampfite's one perfect cleavage. Kampfite shares chemical and structural similarities with cymrite. , it is the only known barium silicate

aside from fencooperite.

Occurrence

Kampfite has been found in association with celsian, fresnoite,

macdonaldite Macdonaldite is a rare barium silicate mineral with a chemical formula of BaCa4Si16O36(OH)2·10H2O.Alfors, J.T., Stinson, M.C., Matthews, R.A., and Pabst, A. (1965) Seven new barium minerals from eastern Fresno County, California. American Minera ...

pyrrhotite Pyrrhotite is an iron sulfide mineral with the formula Fe(1-x)S (x = 0 to 0.2). It is a nonstoichiometric variant of FeS, the mineral known as troilite. Pyrrhotite is also called magnetic pyrite, because the color is similar to pyrite and it i ...

, titantaramellite, traskite, and

witherite Witherite is a barium carbonate mineral, Ba C O3, in the aragonite group. Witherite crystallizes in the orthorhombic system and virtually always is twinned. The mineral is colorless, milky-white, grey, pale-yellow, green, to pale-brown. The spec ...

. The mineral is known only from locations in

. Kampfite is found in

quartz Quartz is a hard, crystalline mineral composed of silica ( silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon-oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical ...

-rich regions of sanbornite rocks within

gneiss Gneiss ( ) is a common and widely distributed type of metamorphic rock. It is formed by high-temperature and high-pressure metamorphic processes acting on formations composed of igneous or sedimentary rocks. Gneiss forms at higher temperatures a ...

which has undergone

contact metamorphism Metamorphism is the transformation of existing rock (the protolith) to rock with a different mineral composition or texture. Metamorphism takes place at temperatures in excess of , and often also at elevated pressure or in the presence of che ...

associated with an adjacent

granodiorite Granodiorite () is a coarse-grained ( phaneritic) intrusive igneous rock similar to granite, but containing more plagioclase feldspar than orthoclase feldspar. The term banatite is sometimes used informally for various rocks ranging from gr ...

intrusive.

History

The mineral discovered in 1964 by Robert Walstrom from the Esquire #1 claim of the Rush Creek deposit in eastern Fresno County. It was described in 2001 in ''The Canadian Mineralogist''. 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. Co-type specimens are held by the

University of British Columbia The University of British Columbia (UBC) is a public research university with campuses near Vancouver and in Kelowna, British Columbia. Established in 1908, it is British Columbia's oldest university. The university ranks among the top thre ...

and the

Geological Survey of Canada The Geological Survey of Canada (GSC; french: Commission géologique du Canada (CGC)) is a Canadian federal government agency responsible for performing geological surveys of the country, developing Canada's natural resources and protecting the e ...

References

Bibliography

* *{{cite journal, last1=Basciano, first1=Laurel C., last2=Groat, first2=Lee A., title=The crystal structure of kampfite, journal=The Canadian Mineralogist, year=2007, volume=45, issue=4, pages=935–943, doi=10.2113/gscanmin.45.4.935, url=http://rruff.info/doclib/cm/vol45/CM45_935.pdf

External links

Photos of kampfite
from mindat.org Barium minerals Carbonate minerals Phyllosilicates Monoclinic minerals Minerals in space group 9