Ilyukhinite is a very rare mineral of the eudialyte group, with formula (H3O,Na)14Ca6Mn2Zr3Si26O72(OH)2·3H2O. The formula given is simplified and does not show the presence of cyclic silicate groups. Ilyukhinite is the second group representative with species-defining hydronium ion after aqualite.
- Category: Silicate mineral, Cyclosilicate
- Formula: (H3O,Na)14Ca6Mn2Zr3Si26O72(OH)23H2O
- Crystal system: Trigonal
- Crystal class: Ditrigonal pyramidal (3m)
The Mohs hardness is 5; cleavage is not observed.
- Luster: Vitreous
- Colour: Brownish-orange
- Hardness: 5 on the Mohs scale
- Cleavage: None Observed
- Density: 2.67(2) g/cm3 (Measured) and 2.703 g/cm3 (Calculated)
Occurrence: In hydrothermally-altered peralkaline pegmatite. It occurs as brownish orange, with vitreous luster anhedral grains up to 1 mm across in hydrothermally altered peralkaline rock, in association with aegirine, murmanite, albite, microcline, rhabdophane-(Ce), flu-orite, sphalerite and molybdenite.
Association: Aegirine, murmanite, albite, microcline, rhabdophane-(Ce), fluorite, sphalerite, molybdenite.