porphyry

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  10. [igneous rock by composition]
  11. [igneous rock by composition: physical]
  12. porphyry
Scope note
A dark purplish-red rock, first quarried in ancient Egypt, containing relatively large crystals in a fine-grained igneous matrix. One of the hardest rocks, it takes a high polish and is valued as a durable sculptor's material and as a decorative architectural material. It is considered the best material for the muller and slab used for grinding artists' colors.
porphyry
Accepted term: 29-Apr-2024