| | | Geological Survey, 956 National Center, Reston, VA 20192, USA 4 Camborne School of Mines, School of Geography,...presented of chevkinite-group minerals from Canada, USA, Guatemala, Norway, Scotland, Italy and India. The...Patchilyzoned crystals from Virginia and Guatemala contain both perrierite and chevkinite compositions...review compositional variation in minerals of the perrierite subgroup, which can form in a wide range of host...are described. K EY WORDS : chevkinite-group, perrierite, metamictization, distribution. Introduction | | | Journal (article/letter/editorial) | Center, Reston, Virginia 20192, USA ABSTR ACT The composition of chevkinite and perrierite, the most common...expressed by the formula A4BC2D2Si4O22, where A = (La,Ce,Ca,Sr,Th), B = Fe2+, C = (Fe2+,Fe3+,Ti,Al,Zr,Nb)...a linear array with r2 = 0.91. Chevkinite and perrierite are shown to be compositionally distinct on the...fenites associated with carbonatite complexes. Perrierite is more commonly recorded from igneous rocks...are reviewed briefly. K EY WORDS : chevkinite, perrierite, compositional variation. Introduction T HE | | Macdonald, Ray, Bagiński, Bogusław, Belkin, Harvey E., Stachowicz, Marcin (2019) Composition, paragenesis, and alteration of the chevkinite group of minerals. American Mineralogist, 104 (3) 348-369 doi:10.2138/am-2019-6772 | Journal (article/letter/editorial) | LA1 4YQ, U.K. 3 11142 Forest Edge Drive, Reston, Virginia 20190-4026, U.S.A. Abstract The chevkinite-group...MO6 coordination. In the asymmetric unit of the perrierite-type structure, there are two A sites (A1 and...abundant members of the group are chevkinite and perrierite, which are structurally different. Haggerty and...(chevkinite ~100°, perrierite ~113°). The CGM could then be divided into the chevkinite and perrierite subgroups...angle almost perfectly: Subsequently, the type perrierite-(La) was found to plot just above their suggested | | | Report (issue) | the cover—Turquois crystals from Lynch Station, Virginia; x ca.; pho tograph by Neal Ycdlin; color plates...C. A. Michael. COLD NUGGET FROM SPOTSYLVANIA COUNTY: Longest dimension approximately 13 cm., photograph...of Virginia R. V. DIETRICH* Professor of Geology and Associate Dean of Arts & Sciences, Virginia Polytechnic...Polytechnic Institute Research Division Bulletin 47 Virginia Polytechnic Institute, Blacksburg, Va. 24061 *... © R. V. Dietrich and the Research Division of Virginia Polytechnic Institute, 1970 Printed and bound | | | Journal (issue) | BB I ^ B ^ P JlM University of Virginia, Charlottesville, Virginia 22903 by Richard S. M itchell PART...radii of rareearth elements present (Y unstabilizing, Ce stabilizing) (Holmes, 1931), and radius ratios and...specimens from the Amelia-Powhatan Counties area, Virginia, began to crystallize in air as low as 200°C (one...higher temperatures. In specimens from the Bedford County, Virginia, area a weak priorite phase, accompanied...metamict Davidite, (La,Ce,U)x(U,Fe2 )(Ti,Fe3 )60 i3-x (Ueda, 1957). Loparite, (Na,Ce,Ca)Ti03 The thorian | | | Book | ........ . Y .............. . Ce4............. . Ce 3p5-Th4S·4 l .... . Zr .. ... .... .. ... . Ca ....Other cations Nb-Ta ......... . . (Nb-Ta)-Ti ...... . Ce-Y ......... . . . Ti-Si ......... . . . . Ti-Sn ....... . Ca-Na2.. . ..... . Ca-1(2 .......... . Ca-Ce ........... . Oa-Fe2....... .. . . Ou-Pb .... . ...V None of the uranyl minerals contains Th, Zr, or Ce for uranium, because of the large size and unusual.... . Strongly radioactive types are 1netamict - Ce-earth silicates: Chinglusuite Rinkolite. . . . . |
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