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Silicate

Hellandite-(Y)

(Ca,REE)₄Y₂Al   ₂(B₄Si₄O₂₂)(OH)₂
Hardness4.5–6.5
Crystal systemMonoclinic
ClassSilicate
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Hellandite-(Y) specimen

Hellandite-(Y) Locality: Evans-Lou Mine, Val-des-Monts, Les Collines-de-l'Outaouais RCM, Outaouais, Québec, Canada Yellowish to brown massive Hellandite-(Y). Possible some Kainosite-(Y) is also present. Field of view 7 mm. Specimen and photo Leon Hupperichs. — Photo: Leon Hupperichs · CC BY-SA 3.0

Hellandite-(Y)

Hellandite-(Y) is an IMA-recognized mineral species in the silicate class, with the chemical formula (Ca,REE)₄Y₂Al   ₂(B₄Si₄O₂₂)(OH)₂.

It crystallizes in the monoclinic crystal system (space group P2/a). It is a member of the Hellandite structural group.

Key properties: Mohs hardness 4.5–6.5; specific gravity 2.95–3.63; Vitreous to dull luster; optically biaxial.

IMA symbol Hld-Y, IMA status: approved, named in 1903.

Found in granite pegmatite (Norway; Wakefield Lake, Canada).

It is found associated with Tourmaline, thorite, allanite, apatite, phenakite, zircon, titanite (Kragerö, Norway); quartz, chlorite, fergusonite, kainosite-(Y), tengerite, xenotime.

The name refers to geologist Amund Theodor Helland (1846-1918), of Oslo, Norway. The suffix indicates the dominant REE at the Y site.

Index entry. This entry combines official IMA/RRUFF species data with published physical-property data — a full written entry hasn’t been published yet. Browse more H minerals or help write this entry.