Sorosilicate (Si2O7 groups)
Specific gravity: 4.2
Colour: Flesh-pink, brown or greenish
Solubility: Soluble in hydrochloric and sulphuric acid
Thalénite-(Y) is found in granite pegmatites, associated with
fluorite, quartz and
microcline (HOM, Mindat). It may also occur as replacement veinlets in fluorite variety
yttrofluorite and may include
and yttrialite-(Y) (Dana). Heating dehydrates it and converts it to
The type locality is Österby, St. Skedevi, Säter, Dalarna County, Sweden.
A few miles south of Kingman, Arizona, USA, thalénite occurs as a minor constituent of a single small pegmatite within an extensive area of granite. The pegmatite is made up almost entirely of quartz and microcline; hematite, biotite and zircon are present in minor amounts (AM 71.188-193).
At the White Cloud pegmatite, Jefferson county, and the Snowfake pegmatite, Teller county, both in Colorado, USA, thalénite-(Y) is associated with allanite (Dana).
At the Cripple Creek mining district, Colorado, USA, thalénite-(Y) has been reported as minute crystals in a groundmass of phonolite (Minrec 36-2.182).
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