Definition of porphyroclast in English:

porphyroclast

noun

Geology
  • A relatively large grain remaining in a finer groundmass in a rock which has undergone dynamic metamorphism.

Origin

1930s; earliest use found in Journal of Geology. From porphyro- + -clast, after porphyroclastic.

Pronunciation

porphyroclast

/ˈpɔːfɪrəklɑːst//ˈpɔːfɪrəklast/