Definition of allactite in English:

allactite

noun

Mineralogy
  • A rare reddish-brown or pink mineral consisting of a basic arsenate of manganese, typically occurring as prisms and as crusts on manganese ores.

Origin

Late 19th century; earliest use found in Journal of the Chemical Society. From Swedish allaktit from ancient Greek ἀλλακτ-, stem of ἀλλάσσειν to change (ultimately from ἄλλος other; the guttural suffix is unexplained) + Swedish -it. So called because of the property of changing colour in polarized light depending on the orientation of the crystals (pleochroism).

Pronunciation

allactite

/əˈlaktʌɪt/