Mojaveite and bluebellite, two new minerals from the ...

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late John Jenkins of Redlands, California in 1983 at the shallow D shaft, Blue Bell claims, where world- class specimens of quetzalcoatlite were also found.
Mojaveite and bluebellite, two new minerals from the central Mojave Desert Stuart J. Mills1*, Anthony R. Kampf2, Andrew G. Christy3, Robert M. Housley4, George R. Rossman4, Robert E. Reynolds5, and Joe Marty6 1 Geosciences, Museum Victoria, GPO Box 666, Melbourne 3001, Victoria, Australia; 2Mineral Sciences Department, Natural History Museum of Los Angeles County, 900 Exposition Blvd, Los Angeles, CA 90007, USA; 3Centre for Advanced Microscopy, Australian National University, Canberra, ACT 0200, Australia; 4Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA; 5220 South Buena Vista St, Redlands, CA 92373, USA; 65199 E. Silver Oak Rd, Salt Lake City, UT 84108, USA; *E-mail: [email protected]

The Mojave Desert in the U.S. Southwest contains thousands of old mines and prospects, the vast majority of which were never economically profitable. However, a few deposits, though they produced little ore, have yielded a noteworthy variety of rare and unusual minerals. One of these deposits is the Blue Bell claims in the Soda Mountains, about 11 km west of Baker, San Bernardino County, California, which has been a prolific producer of micro-crystals of rare species for six decades (Crowley 1977; Maynard et al. 1984; Kampf et al. 2009; Mills et al. 2010; Housley et al. 2011). Importantly, the Blue Bell claims are the type locality for the new minerals fluorphosphohedyphane (Kampf and Housley 2011), plumbophyllite (Kampf et al. 2009) and reynoldsite (Kampf et al. 2012b). A little farther east, another world-class

mineral locality is found at Otto Mountain, 1.5 km northwest of Baker. Twelve new secondary minerals (Table 1) have been described from this remarkable mineral assemblage. Here we announce two new minerals, bluebellite and mojaveite, which have recently been approved by the International Mineralogical Association Commission on New Minerals, Nomenclature and Classification.

Fig. 1. Bluebellite with fluorite on murdochite pseudo-morphous after wulfenite (2 mm FOV) from the Blue Bell claims.

Fig. 2. Crystals of mojaveite on quartz (1 mm FOV) from Otto Mountain.

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s. j. mills, a. r. kampf, a. g. christy, r. m. housley, g. r. rossman, r. e. reynolds and j. marty | mojaveite and bluebellite

Bluebellite

Conclusions

Bluebellite, Cu6[IO3](OH)10Cl, was discovered by the late John Jenkins of Redlands, California in 1983 at the shallow D shaft, Blue Bell claims, where worldclass specimens of quetzalcoatlite were also found. Bluebellite occurs as bright bluish-green plates or flakes up to about 20 x 20 x 5 µm in size. Plates are generally curved and are intergrown in irregular aggregates. Bluebellite occurs in direct association with murdochite (often as pseudomorphs after wulfenite; Figure 1), calcite, fluorite, and hemimorphite in a highly siliceous hornfels. Rarely, dioptase is also found in association with bluebellite. Bluebellite crystallizes in the trigonal system, with the space group R3 and unit cell parameters a = 8.3017(5), c = 13.259(1) Å, V = 791.4(1) Å3 and Z = 3. The cotype specimens are housed in the collections of the Natural History Museum of Los Angeles County and Museum Victoria (Australia).

Seventeen minerals new to science have been discovered from the Blue Bell claims and at Otto Mountain in the past five years, but while the majority of unidentified species have been named, there are still many unknowns from these two deposits, which may yet yield new mineral species. These sites are truly remarkable occurrences, not only in California and the USA, but world-wide!

Mojaveite Mojaveite, Cu6[TeO4(OH)2](OH)7Cl, was discovered by one of the authors (JM) in 2005 on Otto Mountain at the Aga mine and Bird Nest drift and in 2011 in the small E pit at Blue Bell. Mojaveite is the tellurate analogue of bluebellite, with Te6+O replacing I5+OH in the crystal structure. Mojaveite occurs as greenish-blue plates, which rarely show a hexagonal outline (Figure 2). The plates are generally curved and are intergrown in irregular aggregates. Mojaveite also occurs as compact balls, varying in colour from sky blue to medium greenish blue. Both individual plates and compact balls reach 0.5 mm in maximum dimension. At the Blue Bell claims, mojaveite occurs in direct association with andradite, cerussite, chlorargyrite, chrysocolla, hemimorphite, kettnerite, perite, quartz and wulfenite. At the Aga mine mojaveite is associated with cerussite, chrysocolla, khinite, perite and quartz. At the Bird Nest drift, it is associated with andradite, chrysocolla, cerussite, burckhardtite, galena, goethite, khinite, mcalpineite, thorneite, timroseite, paratimroseite, quartz and wulfenite. Mojaveite crystallizes in the trigonal system, with the space group R3 and unit cell parameters a = 8.316(2), c = 13.202(6) Å, V = 790.7(1) Å3 and Z = 3. The cotype specimens are also housed in the collections of the Natural History Museum of Los Angeles County and Museum Victoria (Australia). 166

References Crowley, J. A. (1977) Minerals of the Blue Bell mine, San Bernardino County, California. Mineralogical Record, 8, 494‒496, 518. Housley, R.M., Kampf, A.R., Mills, S.J., Marty, J., and Thorne, B. (2011) The remarkable occurrence of rare secondary tellurium minerals at Otto Mountain near Baker, California —including seven new species. Rocks and Minerals, 86, 132‒142. Kampf, A.R. and Housley, R.M. (2011) Fluorphosphohedyphane, Ca 2Pb3(PO4)3F, the first apatite supergroup mineral with essential Pb and F. American Mineralogist, 96, 423‒429. Kampf, A.R., Housley, R.M., Mills, S.J., Marty, J. and Thorne, B. (2010a) Lead–tellurium oxysalts from Otto Mountain near Baker, California: I. Ottoite, Pb2TeO5, a new mineral with chains of tellurate octahedra. American Mineralogist, 95, 1329–1336. Kampf, A.R., Marty, J. and Thorne, B. (2010b) Lead–tellurium oxysalts from Otto Mountain near Baker, California: II. Housleyite, Pb6CuTe4TeO18(OH)2, a new mineral with Cu–Te octahedral sheets. American Mineralogist, 95, 1337–1342. Kampf, A.R., Housley, R.M. and Marty, J. (2010c) Lead–tellurium oxysalts from Otto Mountain near Baker, California: III. Thorneite, Pb6(Te2O10)(CO3)Cl2(H2O), the first mineral with edge-sharing octahedral dimers. American Mineralogist, 95, 1548–1553. Kampf, A.R., Mills, S.J., Housley, R.M., Marty, J. and Thorne, B. (2010d) Lead–tellurium oxysalts from Otto Mountain near Baker, California: IV. Markcooperite, Pb2(UO2)Te6+O6, the first natural uranyl tellurate. American Mineralogist, 95, 1554–1559. Kampf, A.R., Mills, S.J., Housley, R M., Marty, J. and Thorne, B. (2010e) Lead–tellurium oxysalts from Otto Mountain near Baker, California: V. Timroseite, Pb2Cu2+5(Te6+O6)2(OH)2, and paratimroseite, Pb2Cu2+4(Te6+O6)2(H2O)2, new minerals with edge-sharing Cu–Te octahedral chains. American Mineralogist, 95, 1560–1568. Kampf, A.R., Mills, S.J., Housley, R.M., Marty, J. and Thorne, B. (2010f) Lead–tellurium oxysalts from Otto Mountain near Baker, California: VI. Telluroperite, Pb3Te4+O4Cl2, the Te analogue of perite and nadorite. American Mineralogist, 95, 1569–1573. Kampf, A.R., Mills, S.J., Housley, R.M., Rumsey, M.S., and Spratt, J. (2012a) Lead–tellurium oxysalts from Otto Mountain near Baker, California: VII. Chromschieffelinite,

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Pb10Te6O20(CrO4)(H2O)5, the chromate analogue of schieffelinite. American Mineralogist, 97, 212–219. Kampf, A.R., Mills, S.J., Housley, R.M., Bottrill, R.S. and Kolitsch, U. (2012b) Reynoldsite, Pb2Mn4+2O5(CrO4), a new phyllomanganate-chromate from the Blue Bell claims, California and the Red Lead mine, Tasmania. American Mineralogist, 97, 1187‒1192. Kampf, A.R., Mills, S.J., Housley, R.M., and Marty, J. (2013a) Lead–tellurium oxysalts from Otto Mountain near Baker, California: VIII. Fuettererite, Pb3Cu2+6Te6+O6(OH)7Cl5, a new mineral with double spangolite–type sheets. American Mineralogist, 97, 506–511. Kampf, A.R., Mills, S.J., Housley, R.M., and Marty, J. (2013b) Lead-tellurium oxysalts from Otto Mountain near Baker, California: IX. Agaite, Pb3Cu2+Te6+O5(OH)2(CO3), a new mineral with CuO5–TeO6 polyhedral sheets. American Mineralogist, 97, 512–517. Kampf, A.R., Mills, S.J., Housley, R.M., Rossman, G.R., Marty, J., and Thorne, B. (2013c) Lead–tellurium oxysalts from Otto Mountain near Baker, California: X. Bairdite, Pb2Cu2+4Te6+2O10(OH)2(SO4)·H2O, a new mineral with thick HCP layers. American Mineralogist, 97, 1315‒1321. Kampf, A.R., Mills, S.J., Housley, R.M., Rossman, G.R., Marty, J. and Thorne, B. (2013d) Lead–tellurium oxysalts from Otto Mountain near Baker, California: XI. Eckhardite, (Ca,Pb) Cu2+Te6+O5(H2O), a new mineral with HCP stair-step layers. American Mineralogist, 98, 1617‒1623. Kampf, A.R., Rossman, G.R. and Housley, R.M. (2009) Plumbophyllite, a new species from the Blue Bell claims near Baker, San Bernardino County, California. American Mineralogist, 94, 1198‒1204. Maynard, M.F., Valenti, A., Jenkins, J., Jenkins, F., Hall, D., Hall, J., White, B., White, S., Mansfield, M. and Mansfield, E. (1984) The Blue Bell Claims. San Bernardino County Museum Special Publication, San Bernardino County Museum, San Bernardino. Mills, S.J., Kampf, A.R., Kolitsch, U., Housley, R.M., and Raudsepp, M. (2010) The crystal chemistry and crystal structure of kuksite, Pb3Zn3Te6+P2O14, and a note on the crystal structure of yafsoanite, (Ca,Pb)3Zn(TeO6)2. American Mineralogist, 95, 933–938.

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