Slyudyankaite

slyudyankaite

diopside

fluorapatite

lazurite

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Formula: Na₂₈Ca₄(Si₂₄Al₂₄O₉₆)(SO₄)₆(S₆)_1/3(CO₂).2H₂O
Tectosilicate (framework silicate), cancrinite group of the feldspathoid group
Crystal System: Triclinic
Specific gravity: 2.46 measured, 2.454 calculated for the empirical formula
Hardness: 5½
Streak: White
Colour: Green to pale blue
Luminescence: Not fluorescent under UV
Environments

Metamorphic environments

Slyudyankaite is a new mineral, approved in 2021 and to date (September 2023) reported only from the type locality.

Localities

At the type locality, the Malo-Bystrinskoe lazurite deposit, Malaya Bystraya River Valley, Slyudyanka, Lake Baikal area, Irkutsk Oblast, Russia, slyudyankaite was discovered in altered lazurite-bearing metasomatic rock. The associated minerals are diopside, calcite, fluorapatite, phlogopite, lazurite and pyrite. Slyudyankaite forms green to pale blue isolated vitreous anhedral equant grains up to 0.5 cm across and their aggregates (AM 108.1805-1817).

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