Dacite, Isle of Rum, Scotland

This is a thin section microscope slide of a Dacite rock from the Isle of Rum in the Inner Hebrides. Usually known for it's ultramafic rocks this island has quite a variety of different rock types. This is an acid extrusive rock, mainly glassy with flow swirls, but showing minute needles which may be due to devitrification. Phenocrysts of embayed quartz and plagioclase, small amphiboles and mafic area inclusions.

1 Slide

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