Lasnierite

lasnierite

lazulite

monazite-(Ce)

xenotime-(Y)

Images

Formula: (Ca,Sr)(Mg,Fe2+)2Al(PO4)3
Phosphate, strontium-bearing mineral
Specific gravity: 3.162 calculated
Colour: Slightly pale pinkish brown, colourless
Environments

Metamorphic environments

Lasnierite is a relatively new mineral, approved in 2018 and to date (July 2022) reported only from the type locality.

Localities

The type locality is the Lasnierite type locality, Sahatsiho Ambohimanjaka, Ambositra, Amoron'i Mania, Madagascar. Lasnierite was discovered as inclusions in a 1.97 carat faceted lazulite-bearing quartz from Mount Ibity, obtained on the market, and its exact provenance is unknown. The cut stone originated from the lazulite-bearing metaquartzite horizon of sedimentary origin. The metamorphic sequence reached greenschist to amphibolite facies grade, at 450 to 550oC and 3.5 kbar. In addition to quartz and lazulite, the mineral association contains chlorapatite, celestine, monazite-(Ce), xenotime-(Y), augelite, trolleite, svanbergite, goyazite, crandallite, berlinite, anhydrite, ilmenite, titaniferous magnetite, rutile, hematite, muscovite, kyanite, zircon, dumortierite, tourmaline, clinoamphibole and undetermined tin-bearing acicular inclusions.
The lasnierite forms transparent slightly pale pinkish brown euhedral crystals 60 to 120 µm in length on the gem surface. (EJM 31.2.379-388).

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