Portal de Periódicos da CAPES

Strontiohurlbutite, SrBe2(PO4)2, a new mineral from Nanping No. 31 pegmatite, Fujian Province, Southeastern China

2014; Mineralogical Society of America; Volume: 99; Issue: 2-3 Linguagem: Inglês

10.2138/am.2014.4547

1945-3027

Can Rao, Rong Wang, Frédéric Hatert, Xiaojun Gu, Luisa Ottolini, Huan Hu, Chuan Dong, Fabrice Dal Bo, Maxime Baijot,

X-ray Diffraction in Crystallography

Strontiohurlbutite, ideally SrBe 2 (PO 4 ) 2 , is a new member of hurlbutite group discovered in the Nanping No. 31 pegmatite, Fujian province, southeastern China.Crystals are mainly found in zones I, II, and IV; they are platy, subhedral-to-anhedral, with a length from 5 mm to 1.5 mm.Associated minerals mainly include quartz, muscovite, beryl, hurlbutite, hydroxylherderite, apatite-group minerals, and phenakite.Strontiohurlbutite crystals are light blue, translucent-to-transparent, and have vitreous luster.The Mohs hardness is about 6, and the tenacity is brittle.Optically, strontiohurlbutite is biaxial (-), a = 1.563(3), b = 1.569(2), g = 1.572(3) (white light), 2V meas = 68.5(5)°,and exhibits weak dispersion, r > v.The optical orientation is X = b, Y ≈ c.Electron-microprobe and SIMS analyses (average of 16) give SrO 29.30, P 2 O 5 51.05, CaO 0.91, BaO 0.64, and BeO 17.71 wt%; total 99.61 wt%.The empirical formula, based on 8 O apfu, is (Sr 0.81 Ca 0.05 Ba 0.01 ) S0.87 Be 2.02 P 2.05 O 8 .The stronger eight lines of the measured X-ray powder-diffraction pattern [d in Å(I)(hkl)] are: 3.554(100)(121); 3.355(51)(211); 3.073(38)(022); 2.542(67)(113); 2.230(42)(213); 2.215(87)(321); 2.046(54)(223); 1.714(32)(143).Strontiohurlbutite is monoclinic, space group P2 1 /c; unit-cell parameters refined from single-crystal X-ray diffraction data are: a = 7.997(3), b = 8.979(2), c = 8.420(7) Å, b = 90.18(6)°,V = 604.7(1)Å 3 (Z = 4, calculated density = 3.101 g/cm 3 ).The mineral is isostructural with hurlbutite, CaBe 2 (PO 4 ) 2 , and with paracelsian, BaAl 2 Si 2 O 8 .The formation of strontiohurlbutite is related to the hydrothermal alteration of primary beryl by late Sr-and P-rich fluids.