Definition of greisen in English:

greisen

noun

Geology
  • A light-colored rock containing quartz, mica, and fluorine-rich minerals, resulting from the alteration of granite by hot vapor from magma.

    • ‘A greisen is a quartz - mica aggregate containing significant amounts of cassiterite, wolframite, fluorite, topaz, rutile, and tourmaline.’
    • ‘Eventually we reached the site, a few trenches along veins of greisen.’
    • ‘It has been collected in a road cut near Grant Mills, Cumberland, Rhode Island; in Stratford, Fairfield County, Connecticut; and in greisen with purple fluorite at Irish Creek, Rockbridge County, Virginia.’

Origin

Late 19th century: from German, probably a dialect word, from greis ‘gray with age’.

Pronunciation

greisen

/ˈɡrīzən/