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NEW MINERAL NAMES^*

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 K1A 0E8, Canada

The first 20% of the full text of this article appears below.

Bigcreekite^*
L.C. Basciano, L.A. Groat, A.C. Roberts, R.A. Gault, G.E. Dunning, R.E. Walstrom (2001) Bigcreekite: a new barium silicate mineral species from Fresno County, California. Can. Mineral., 39, 761–768.

Four listed electron microprobe analyses, with high totals because of water loss, average Na₂O 0.11, CaO 0.03, SrO 0.02, BaO 48.88, SiO₂ 38.16, H₂O (calc.) 22.94, sum 110.14 wt%, corresponding to Ba_1.00Na_0.01Si_2.00O₅•4H₂O, ideally BaSi₂O₅•4H₂O. Occurs as white to colorless, millimeters-long, subhedral tabular grains, elongate [100]. Brittle, white streak, vitreous to pearly luster, H = 2–3, perfect {010} and {001} cleavages, uneven fracture, nonfluorescent, D_meas = 2.66, D_calc = 2.76 g/cm³ for Z = 4. Optically biaxial positive, = 1.537(2), ß = 1.538(2), = 1.541(2), 2V_meas = 59.2(5), 2V_calc = 60°, moderate dispersion r < v, nonpleochroic, orientation X = b, Y = a, Z = c. Single-crystal X-ray structure study (R = 0.035) indicated orthorhombic symmetry, space group Pnma, a = 5.038(6), b = 9.024(3), c = 18.321(6) Å as refined from a Debye–Scherrer powder pattern (114 mm, CuK radiation) with strongest lines of 5.068 (100,013), 4.054(85,022), 2.974(45,031), 2.706 (60,124), 2.327(40,035), and 2.257(75,126).

The mineral occurs within fractures, <0.5 mm wide, transverse to sanbornite-quartz gneiss at the Esquire no. 7 claim along Big Creek, Fresno County, California. The new mineral name is for the type locality. The mineral also occurs as a fracture fill in lenses of barium silicates, including sanbornite, at Trumbull Peak, Mariposa County, California. Type material is in the M.Y. Williams Museum at the University of British Columbia, Vancouver, Canada. J.L.J.

Clearcreekite^*
A.C. Roberts, L.A. Groat, M. Raudsepp, T.S. Ercit, R.C. Erd, E.A. Moffat, J.A.R. Stirling (2001) Clearcreekite, a new polymorph of Hg₃¹⁺(CO₃)(OH)•2H₂O, from the Clear Creek claim, . . . [Full Text of this Article]

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