Definition of pegmatite in English:

pegmatite

noun

Geology
  • A coarsely crystalline granite or other igneous rock with crystals several centimetres in length.

    ‘tourmaline occurs mainly in granites, pegmatites, and greisens’
    mass noun, as modifier ‘pegmatite dykes’
    • ‘Huge crystals of excellent color are still being found here in pegmatites.’
    • ‘Apatite is the most common phosphate mineral found in granitic pegmatites.’
    • ‘Ed would drill by hand and blast away the rock, exposing the pegmatite.’
    • ‘It is a large area of granite hills in which numerous pegmatites have been found through the years.’
    • ‘It has also been found as a constituent of granites and in granitic pegmatites.’

Origin

Mid 19th century: from Greek pēgma, pēgmat- ‘thing joined together’ + -ite.

Pronunciation

pegmatite

/ˈpɛɡmətʌɪt/