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Formula: Y(PO4).2H2O
Hydrated normal phosphate, yttrium-bearing mineral
Crystal System: Monoclinic
Specific gravity: 3.14 measured, 3.2 calculated
Hardness: 3
Streak: White
Colour: Colourless, white, grey, yellow, colourless in transmitted light
Solubility: Soluble in hot acids, insoluble in alkalies
Environments
Carbonatites
Hydrothermal environments
Churchite-(Y) is typically derived from meteoric waters, with yttrium weathered or
biochemically leached from trace amounts in surrounding rocks or soil, deposited on colloidal
iron-manganese oxides; less commonly it occurs as
a secondary mineral in hydrothermal mineral deposits. Associated minerals
include florencite, rhabdophane,
wavellite, crandallite,
turquoise, variscite,
cacoxenite, beraunite,
dufrénite, goyazite,
gorceixite, crandallite,
monazite, apatite,
todorokite, lithiophorite,
hematite, limonite and
clay minerals
(HOM ).
Localities
At the Mount Weld mine, Mount Weld Station, Laverton Shire, Western Australia, churchite-(Y) occurs in carbonaceous
laterite where it occurs as void fillings in
crandallite group minerals, as fine grains, or intergrown with
limonite and associated with goyazite,
gorceixite, florencite,
crandallite, monazite,
apatite and cerianite-(Ce)
(Dana).
The type locality is the Maffei Mine, Nitzlbuch, Auerbach in der Oberpfalz, Amberg-Sulzbach District, Upper Palatinate, Bavaria,
Germany.
In Kazakhstan churchite-(Y) occurs in the mantle of weathered metamorphic rocks as crystallites up to 12 microns long
associated with apatite, fluorite,
amphiboles, and acicular transparent zeolites,
possibly natrolite
(Dana).
At Chuktukon carbonatite massif, Chadobets alkaline complex, Boguchansky District, Krasnoyarsk Krai, Russia, churchite-(Y)
occurs in laterite
(Dana).
At Wheal Pendarves, Killivose, Camborne, Cornwall, England, UK, churchite-(Y) is associated with
limonite, quartz and
baryte
(Dana).
At the Kelly Bank mine, Lyndhurst-Vesuvius Mining District, Rockbridge county, Virginia, USA, specimens of manganiferous iron oxide
were coated with minute specks of whitish radially fibrous aggregates of churchite-(Y), the largest less than a
millimeter across, and characteristically coating brown siliceous limonite or black
manganese oxide. The hemispherical rosettes frequently have a dusty brownish surface; many of them when broken show concentric
black zones orcores of manganese dioxide
(AM 29.92-107 {as Weinschenkite}).
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