Accession Number : AD0767437

Title :   New Technique and Indicators for Studies of Growth History of Zoned Crystals.

Descriptive Note : Final rept. 1 Nov 69-30 Sep 73,

Corporate Author : GEORGIA TECH RESEARCH INST ATLANTA

Personal Author(s) : Pollard,Charles O. , Jr

Report Date : 31 AUG 1973

Pagination or Media Count : 87

Abstract : Two X-ray diffraction imaging techniques have been applied for the first time to the study of previously unnoted mosaic detail in color-zoned Brazilian tourmaline. The divergence source-image distortion (DSID) technique gives maximum values for misorientations among all observable grains, whereas the convergence source-image distortion (CSID) technique yields the magnitude of misorientation between adjacent grains. Strikingly abrupt textural changes are observed; they are always accompanied by color changes. The converse is not found to hold. The central or core region of all five plates studied shows a macromosaic texture. No grain elongation is observed. AT-cut quartz crystals can be made to Dauphine twin by torsion at above 600C, such that the twin boundaries assume veil-like shapes with steps, except where they correspond to pre-existing growth horizon boundaries. Strain rate controls and recording are needed to exclude problems with fracturing. (Author)

Descriptors :   (*CRYSTAL STRUCTURE, *X RAY DIFFRACTION), (*MINERALS, X RAY DIFFRACTION), CRYSTAL GROWTH, COLORS, TOURMALINE, QUARTZ, TWINNING(CRYSTALLOGRAPHY)

Subject Categories : Geology, Geochemistry and Mineralogy
      Crystallography

Distribution Statement : APPROVED FOR PUBLIC RELEASE