Pilawite-(Y)

pilawite-(Y)

keiviite-(Y)

gadolinite-(Y)

hingganite-(Y)

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Formula: Ca₂Y₂Al₄(SiO₄)₄O₂(OH)₂
Nesosilicate (insular SiO₄ groups)
Crystal System: Monoclinic
Specific gravity: 4.007 calculated
Hardness: 5
Streak: White
Colour: White
Environments

Pegmatites

Pilawite-(Y) is a relatively new mineral, approved in 2013 and to date (November 2023) reported only from the type locality.

Localities

At the type locality, the Julianna pegmatite, DSS Piława Górna Quarry, Piława Górna, Dzierżoniów County, Lower Silesian Voivodeship, Poland, pilawite-(Y) has been found within the blocky feldspar zone of a weakly zoned and weakly fractionated niobium - yttrium - fluorine affiliated granitic pegmatite dike. It occurs as white, translucent, brittle crystals up to 1.5 mm in size, with a white streak, vitreous lustre and a hardness of 5 on Mohs scale. The pilawite-(Y)-bearing assemblage crystallised in the sequence: keiviite-(Y) → gadolinite-(Y) to hingganite-(Y) + hellandite-(Y) → pilawite-(Y) → allanite-(Y) → epidote/zoisite. (MM 79.5.1143-1157, HOM).

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