Images
Formula: Al71Ni24Fe5
Alloy of aluminium, nickel and
iron
Crystal System: Icosahedral
Colour: Grey to black
Environments
Decagonite is a natural quasicrystal phase, second to be discovered and approved after
icosahedrite. See
Mindat for a description of quasicrystals.
Decagonite is a relatively new mineral, approved in 2015 and to date (February 2025) reported only from the
type locality.
Localities
At the type locality, the Khatyrka meteorite, Iomrautvaam massif, Anadyrsky District, Chukotka Autonomous Okrug,
Russia, decagonite was found as rare fragments up to ~60 microns across in one of the grains (labeled
number 126) of the carbonaceous chondrite. The
meteoritic grain contains evidence of a heterogeneous
distribution of pressures and temperatures that occurred during impact shock, in which some portions of the
meteorite reached at least 5 GPa and 1200°C.
Decagonite is associated with aluminium-bearing
trevorite, diopside,
forsterite, ahrensite,
clinoenstatite, nepheline,
coesite, pentlandite,
copper-bearing troilite,
icosahedrite, khatyrkite,
taenite,
aluminium-bearing taenite and
steinhardtite
(AM 100.2340–2343).
Decagonite from the Khatyrka Meteorite -
Image
Back to Minerals