Definition of microfelsitic in US English:

microfelsitic

adjective

Geology
  • Of a rock: showing signs of incipient crystallization without there being any actual crystals; cryptocrystalline.

Origin

Late 19th century; earliest use found in Frank Rutley (1842–1904), geologist. From micro- + felsitic, after German mikrofelsitisch.

Pronunciation

microfelsitic

/ˌmʌɪkrə(ʊ)fɛlˈsɪtɪk/