Image: Porphyritic trachyte

Porphyritic trachyte

Porphyritic trachyte (12.5 cm x 9 cm). Upper Fine Flower Rd, Coaldale area, New South Wales.

Photographer:
Stuart Humphreys
Rights:
© Australian Museum

Notes

Trachyte is a volcanic rock composed largely of alkali feldspar. Porphyry is a general term for igneous rocks that contain phenocrysts (larger crystals) in a finer-grained groundmass.

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Tags igneous rocks, volcanic, volcanoes, mineralogy, geosciences,