Definition of porphyroclastic in US English:

porphyroclastic

adjective

Geology
  • Of a rock or its texture: marked by the presence of porphyroclasts.

Origin

1920s; earliest use found in Arthur Holmes (1890–1965), geologist and geophysicist. From porphyro- + clastic, after German porphyroklastisch.

Pronunciation

porphyroclastic

/ˌpɔːfɪrə(ʊ)ˈklastɪk/