This micrograph shows plagioclase, a type of feldspar, with a field of view of 2.7 mm. The sample hails from Brazil, and Bernardo Cesare, a geoscientist at the University of Padua, obtained it from a company that sells marble and granite for countertops. The plagioclase shown here is twinned, which refers to crystals that share lattice points but have different orientations. The blue areas all have the same orientation, and the yellow areas have a different orientation. Twinned plagioclase is found in igneous and metamorphic rocks all over the world. “In geology the composition of plagioclase is extensively used to determine the pressure and temperature of rock formation,” Cesare explains. Plagioclase is also commonly used as a raw material in the ceramics industry.
Credit: Bernardo Cesare
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