MinIdent-Win - benitoite Get a copy of MinIdent-Win at http://www.micronex.ca/index.php?idx=10 Formula: BaTiSi3O9 Status: Mineral name is IMA approved or traditional Kretz abbreviation: Bst Level: Species First Described in 1907 Parents: benitoite-group Symmetry: Hexagonal Space Group: P-6c2 Mean Atomic Number: 26.8 Diffraction Values: 3.717, 2.738, 2.872, 5.740, 2.172 ICDD (TM) Number: 26-1036 Minimum Maximum Average Std. Dev. a (A) 6.600 6.642 6.640 b (A) 6.600 6.642 6.640 c (A) 9.710 9.761 9.758 Alpha 90.000 90.000 90.000 Beta 90.000 90.000 90.000 Gamma 120.000 120.000 120.000 Volume 366.301 372.926 372.587 Minimum Maximum Average Std. Dev. n(Omega) 1.755 1.757 1.757 n(Epsilon) 1.799 1.804 1.804 Max. birefringence0.047 0.047 0.047 Optical Sign: +ve C(Omega) Colourless C(Epsilon) Blue, Pale Blue, Purpleish Blue Minimum Maximum Average Std. Dev. Mohs 6.0 6.5 6.0 Vickers 771 943 771 Density 3.62 3.69 3.65 Total Min Anal. Min Average Anal. Max Total Max Average Coordination Wt (%) Wt (%) Wt (%) Wt (%) Wt (%) Atomic O 34.4309 34.4309 34.7504 34.9975 35.1721 9.0000 Na 0.0000 0.0000 0.0668 0.1039 0.1039 0.0120 Mg 0.0000 0.0000 0.0020 0.0060 0.0060 0.0003 Al 0.0000 0.0000 0.0424 0.1059 0.1059 0.0065 Si 19.9223 19.9223 20.1568 20.4014 20.5830 2.9735 4 Ca 0.0000 0.0000 0.0253 0.0715 0.0715 0.0026 Ti 11.4679 11.6544 11.7394 11.8673 11.8673 1.0156 6 V 0.0000 0.0000 0.0010 0.0020 0.0020 0.0001 Fe 0.0000 0.0000 0.0156 0.0389 0.0389 0.0012 Sr 0.0000 0.0000 0.0023 0.0040 0.0040 0.0001 Zr 0.0000 0.0000 0.0307 0.0800 0.0800 0.0014 Nb 0.0000 0.0000 0.0467 0.1400 0.1400 0.0021 Sn 0.0000 0.0000 0.0000 3.2294 3.2294 0.0000 Ba 32.8439 32.8439 33.1902 33.3813 33.5454 1.0014 6 Total 100.0699 14.0169 Atomic proportions calculated for O = 9.0 Compilation based on 4 general and 4 sample records Values in italics are calculated from the minimum and maximum values. Other data are from the sample and general records. Page 1 - 04/03/2010 MinIdent-Win - benitoite Get a copy of MinIdent-Win at http://www.micronex.ca/index.php?idx=10 Lustre Vitreous, Subadamantine Habit Prismatic, Dipyramidal, Pyramidal, Tabular, Triangular Tenacity Brittle Fracture Uneven, Subconchoidal, Conchoidal Cleavage {10-11} Indistinct Surface Colour Pale Blue, Blue, Dark Blue, Greyish Blue, Bluish Grey, Purple, Pink, White Streak Colourless, White Fluor. Short Blue Other lumin. Cathodoluminescent: Blue Notes on hand specimen data: Pleochroism (blue to colourless) visible by the naked eye using any partially polarised light source (e.g., reflected sunlight). May be varigated in colour. Remarks: May be colourless, white or pink but is usually blue or purple. Sometimes varigated. Streak is white. Transparent to translucent with a vitreous lustre. May show strong bluish fluorescence under short wave UV light. Brittle with an uneven to conchoidal fracture and indistinct cleavage. Pyramidal or tabular crystals. Occurrences: In veins in brecciated blueschist facies rocks, associated with serpentine, neptunite, crossite, albite and natrolite. Localities of samples used in compilation: Near new Idria, San Benito County, California, U.S.A. References: Amer. Min. v.50, p.1164-1169.; v.57, p.85-102. Roberts et al. (1974) Encycl. Mins. Phillips & Griffen (1981) Opt. Min. USGS Bull. 1627. Page 2 - 04/03/2010.