Definition of pseudomorph in US English:



  • A crystal consisting of one mineral but having the form of another which it has replaced.

    • ‘Similar malachite masses weighing up to 3 tons as well as malachite pseudomorphs after cuprite crystals to 2 cm have been found in the mine.’
    • ‘Close examination of the drift and crosscut revealed two crystal-bearing zones, where two large vugs were discovered that contained superb quartz encrustation pseudomorphs of calcite crystals.’
    • ‘In one isolated occurrence, aggregates of small cerussite crystals form pseudomorphs, less than 2 mm across, after an unknown mineral.’
    • ‘Amazing and fantastic forms of representatives of the mineral world are displayed in the exhibitions dedicated to crystals, mineral aggregates, and pseudomorphs.’
    • ‘The idea that tiger's-eye is a pseudomorph - a mineral in which crystals of one material take on the form of another, which it replaces atom by atom - held sway for more than 125 years.’


[with object]Crystallography
  • Replace (another substance) to form a pseudomorph.

    ‘actinolite and hornblende typically pseudomorph pyroxene’
    • ‘Andalusite porphyroblasts that overgrow the S 1 fabric were pseudomorphed by colourless mica.’
    • ‘The most common secondary uranium mineral at the mine, it is typically associated with sooty black organic material and may pseudomorph it.’
    • ‘Titanite is less conspicuous and often pseudomorphed by carbonate and rutile; allanite more so in euhedral crystals up to I cm in length.’
    • ‘Relict coarse, lath-shaped omphacites are variably preserved, but all are either partially retrogressed to pargasite or have been pseudomorphed by diopside-plagioclase symplectites.’
    • ‘Foord reported that bastnasite has been found pseudomorphing allanite.’


Mid 19th century: from pseudo- ‘false’ + Greek morphē ‘form’.