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Oxides & Hydroxide

Hydroxycalciomicrolite

Ca₁.₅Ta₂O₆(OH)
Hardness5–6
Crystal systemCubic
ClassOxides & Hydroxide
←PrevHydroxyapophyllite-(K)NextHydroxycalciopyrochlore→
Hydroxycalciomicrolite specimen

Hydroxycalciomicrolite, 3 tiny bright green crystals (0.2-0.3 mm.), off matrix. K. Nash specimen (MM105). From: Fisher Quarry, Topsham, Sagadahoc Co., Maine, USA. — Photo: Kelly Nash · CC BY 3.0

Hydroxycalciomicrolite

Hydroxycalciomicrolite is an IMA-recognized mineral species in the oxides & hydroxide class, with the chemical formula Ca₁.₅Ta₂O₆(OH).

It crystallizes in the cubic crystal system. It is a member of the Pyrochlore-microlite structural group.

Key properties: Mohs hardness 5–6; specific gravity 6.176; White streak; Vitreous to resinous luster.

IMA symbol Hcmic, IMA status: approved, named in 2013.

Found in heavy mineral concentrates from a complex granitic pegmatite.

It is found associated with Hydrokenomicrolite, fluorcalciomicrolite (in the same concentrate sample).

The name refers to a member of the microlite group with prefixes to indicate dominant OH- (hydroxy) in the Y site and dominant Ca (calcio) in the A 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.