Electronic Resource
Springer
Contributions to mineralogy and petrology
34 (1972), S. 304-314
ISSN:
1432-0967
Source:
Springer Online Journal Archives 1860-2000
Topics:
Geosciences
Notes:
Abstract Variations of structure and optical properties in anorthites (An 93–97%) of different origin are analyzed with the petrographic microscope, U-stage methods, X-ray single crystal analysis and high voltage electron microscopy. No significant variation has been found in the orientation of the indicatrix and of the lattice constants. But c-type reflections (h + k even, ι odd) are strong and sharp in anorthites from slowly cooled rocks and diffuse in anorthites of identical chemical composition from quenched igneous rocks. Large type c-antiphase domains (5000–10000 Å) are found in the slowly cooled rocks, c-domains in volcanic rocks are small (100 Å) or could not be imaged. The presence of only b-domains in lunar basalt 14310 indicates quenching of this rock. Large c-domains in the Apollo 15 genesis rock (15415, Lally et al., 1972) indicate slow cooling similar to terrestrial metamorphic rocks.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00373760
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