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1 Department of Earth and Ocean Sciences, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
2 Geological Survey of Canada, 601 Booth Street, Ottawa, Ontario K1A 0E8
3 Research Division, Canadian Museum of Nature, P.O. Box 3443, Station D, Ottawa, Ontario K1P 6P4, Canada
4 773 Durshire Way, Sunnyvale, California 94087, U.S.A.
5 U.S. Geological Survey, Denver Federal Center, Denver, Colorado 80225, U.S.A.
6 Geological Survey of Canada, 601 Booth Street, Ottawa, Ontario K1A 0E8, Canada
7 P.O. Box 1728, Silver City, New Mexico 88062, U.S.A.
E-mail address: lgroat{at}eos.ubc.ca
Kampfite, ideally Ba6[(Si,Al)O2]8(CO3)2Cl2(Cl,H2O)2, is a newly identified mineral species found in barium-silicate-rich deposits at Big Creek and Rush Creek, Fresno County, California. It forms irregular masses up to 10 mm in size enclosed in quartz-rich portions of the sanbornite-bearing rock. It is light blue-grey, with one perfect cleavage on {001}. Other physical properties are: brittle, translucent, nonfluorescent, vitreous luster, white streak, hardness 3, uneven fracture. Kampfite is uniaxial negative, 
1.642(2), 
1.594(2), nonpleochroic. It is hexagonal, with unit-cell parameters refined from powder data: a 5.244(2), c 29.83(1) Å, V 710.5(4) Å3, and Z = 1. The strongest seven lines of the X-ray powder-diffraction pattern [d in Å(I)(hkl)] are: 14.67(100)(002), 3.883(100)(104), 3.357(50)(106), 2.988(60)(00
), 2.887(50)(108), 2.616(70)(110), and 1.969(50)(11). Precession photographs show that possible space-groups are P63/mmc, P
2c, P63mc, P
1c and P31c. The empirical formula of kampfite (based on the average of three electron-microprobe analyses, normalized on 26 anions) is: (Ba5.83Na0.04Ca0.02)
5.89[(Si5.18Al2.36)7.54O15.08](CO3)2Cl2[(H2O)Cl0.45]1.45. The calculated density is 3.51 g/cm3. All crystals studied contain inclusions or are multiple. Thus, it was not possible to unambiguously determine the correct space-group or precise details of the structure. However, the preliminary results show that the structure is based on double layers of tetrahedra, [T4O8]
, consisting of six-membered rings, with three layers of Ba polyhedra connecting the layers of tetrahedra. Kampfite is part of the monteregianite-(Y) – wickenburgite series (Strunz classification) and is structurally and chemically similar to cymrite. The mineral name honors Anthony R. Kampf, Los Angeles County Museum of Natural History, for his many significant contributions to the study of new and rare minerals.
Keywords: kampfite, new mineral species, barium chloride silicate carbonate hydrate, X-ray data, electron-microprobe data, Big Creek, Rush Creek, Fresno County, California.
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