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 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 ...
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 ]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 ...
.[ 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