Brown cathodoluminescence colour of quartz is suggestive of ................. provenance.
MH SET - 2019, SET Exam - 2019,
Answer: D
Brown cathodoluminescence of quartz suggests a regionally metamorphosed rock source.
Cathodoluminescence colour reflects the temperature of crystallisation and the trace elements and defects in quartz. In the provenance scheme widely used in sandstone petrography, violet to blue luminescing quartz comes from plutonic and volcanic rocks that crystallised at high temperature, brown luminescence is typical of quartz from regionally metamorphosed (especially low-grade) rocks, and authigenic quartz does not luminesce.
So plutonic and volcanic quartz are linked with blue-violet colours rather than brown, and pegmatitic quartz is not a separate brown-luminescing class.
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