Optic properties of centimeter-sized crystals determined in air with the spindle stage using EXCALIBRW
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Mickey E. Gunter
, Robert T. Downs
Abstract
Extinction data sets for four centimeter-sized anisotropic crystals were collected in air with standard spindle-stage methods and submitted to a new Windows-based version of EXCALIBR, termed EXCALIBRW. EXCALIBRW solved these data sets with varying degrees of accuracy related to the external shape of the crystal: the more rounded the crystal, the more precise the results. For an olivine crystal ground into a sphere, the results were similar to those obtained for a crystal immersed in an index-matching fluid. However, even for samples bounded with growth or cleavage faces, the program determined the orientation of the optical indicatrix and 2V with an error of only 1−2°. Thus, this logical extension of spindle-stage methods is helpful: (1) to orient centimeter-size single crystals for various types of mineralogical measurements (e.g., spectroscopy or diffusion studies in which it might be undesirable to place the sample in a liquid); (2) as a non-destructive means of identifying gemstones based upon a determination of their optical class (i.e., isotropic vs. uniaxial vs. biaxial); and (3) for optical characterization by determination of 2V. In addition, the newest version of EXCALIBR is easier to use, mathematically more robust in its solution algorithms, and provides solutions for crystals in less favorable orientations than the earlier versions of EXCALIBR.
© 2015 by Walter de Gruyter Berlin/Boston
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Articles in the same Issue
- Presidential Address To The Mineralogical Society Of Amrica, Boston, November 6, 2001: Some Precambrian Banded Iron-Formations (BiIFs) From Around The World: Their Age, Geologic Setting, Mineralogy, Metamorphism, Geochemistry, And Origin
- Effects of high pressure and high temperature on cation ordering in magnesioferrite, MgFe2O4, using in situ synchrotron X-ray powder diffraction up to 1430 K and 6 GPa
- Raman spectroscopy and vibrational analyses of albite: From 25 °C through the melting temperature
- A new occurrence of xitieshanite [Fe3+(SO4)Cl⋅6H2O] crystals in acid-mine seepways, Green Valley, Vigo County, Indiana, U.S.A.
- Effect of A-site cation radius on ordering of BX6 octahedra in (K,Na)MgF3 perovskite
- Crystal chemistry of NaMgF3 perovskite at high pressure and temperature
- Hyperfine electric field gradient tensors at Fe2+ sites in octahedral layers: Toward understanding oriented single-crystal Mössbauer spectroscopy measurements of micas
- Does the bazhenovite structure really contain a thiosulfate group? A structural and spectroscopic study of a sample from the type locality
- Light-induced degradation dynamics in realgar: in situ structural investigation using single-crystal X-ray diffraction study and X-ray photoelectron spectroscopy
- Absolute quantification by powder X-ray diffraction of complex mixtures of crystalline and amorphous phases for applications in the Earth sciences
- Detrital illite crystals identified from crystallite thickness measurements in siliciclastic sediments
- High-temperature density of lanthanide-bearing Na-silicate melts: Partial molar volumes for Ce2O3, Pr2O3, Nd2O3, Sm2O3, Eu2O3, Gd2O3, Tb2O3, Dy2O3, Ho2O3, Er2O3, Tm2O3, and Yb2O3
- Coupled dichotomies of apatite and fluid composition during contact metamorphism of siliceous carbonate rocks
- The effect of zoned garnet on metapelite pseudosection topology and calculated metamorphic P-T paths
- Low-pressure and low-temperature K-bearing kosmochloric diopside from the Osayama serpentinite mélange, SW Japan
- Dehydration of natural stilbite: An in situ FTIR study
- Structural changes accompanying the phase transformation between leadhillite and susannite: A structural study by means of in situ high-temperature single-crystal X-ray diffraction
- Optic properties of centimeter-sized crystals determined in air with the spindle stage using EXCALIBRW
- Zoltaiite, a new barium-vanadium nesosubsilicate mineral from British Columbia: Description and crystal structure
- Mn-tourmaline from island of Elba (Italy): Crystal chemistry
- Letter: An infrared study of carbon-oxygen bonding in magnesite to 60 GPa
- Letter: Metals in quartz-hosted melt inclusions: Natural facts and experimental artifacts
- Letter: A high-pressure phase transition of calcite-III
- Letter: Experimental observation of an interface-controlled pseudomorphic replacement reaction in a natural crystalline pyrochlore
- Letter: A natural scandian garnet