New Technique and Indicators for Studies of Growth History of Zoned Crystals.
Final rept. 1 Nov 69-30 Sep 73,
GEORGIA TECH RESEARCH INST ATLANTA
Pagination or Media Count:
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
- Geology, Geochemistry and Mineralogy