Ilmajokite-(Ce)

ilmajokite-(Ce)

mountainite

nahcolite

aegirine

Images

Formula: Na₁₁KBaCe₂Ti₁₂Si_37.5O₉₄(OH)₃₀.29H₂O
Unclassified silicate
Crystal System: Monoclinic
Specific gravity: 2.2
Hardness: 1
Streak: White
Colour: Bright yellow
Solubility: Decomposed by water at 20", giving amorphous silica, and by acids giving slight effervescence and amorphous silica gel (AM 58.139-140)
Common impurities: Zr,Al,TR,Fe,Nb,Ta,Ca,Sr,K,C
Environments

Pegmatites

Ilmajokite-(Ce) is a silicate with an extremely complex structure, known to date (March 2025) only from the type locality. It disintegrates rapidly in air (Webmin).

Localities

At the type locality, the Yubileinaya pegmatite, Karnasurt Mountain, Lovozersky District, Murmansk Oblast, Russia, ilmajokite-(Ce) forms granular deposits, crusts, and brushes of crystals up to 2 mm long on the walls of cavities in the central natrolitic zone of the pegmatites. Associated minerals include pale sphalerite, halite, mountainite, nahcolite and aegirine (AM 58.139-140, HOM)
Ilmajokite-(Ce) from the Yubileinaya pegmatite - Image

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