Zeophyllite

zeophyllite

zeolite

apophyllite

manganotantalite

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Formula: Ca₁₃Si₁₀O₂₈(OH)₂F₈.6H₂O
Phyllosilicate (sheet silicate)
Crystal System: Trigonal
Specific gravity: 2.747 to 2.764 measured, 2.75 calculated
Hardness: 3
Streak: White
Colour: White
Common impurities: Al,Fe,Mg,Na,K
Environments

Pegmatites
Metamorphic environments
Hydrothermal environments

Localities

At the Poudrette quarry, Mont Saint-Hilaire, La Vallée-du-Richelieu RCM, Montérégie, Quebec, Canada, zeophyllite occurs in marble xenoliths in nepheline syenite in an intrusive alkalic gabbro-syenite complex. Associated minerals include zeolites and apophyllite (HOM).

At the type locality, Velké Březno, Ústí nad Labem District, Ústí nad Labem Region, Czech Republic, zeophyllite forms radiating platy crystals to 1 cm, as a secondary mineral derived from hydrothermal alteration of basalt and associated with zeolites and apophyllite (HOM).

At the Khibiny Massif, Murmansk Oblast, Russia, zeophyllite occurs as a late-stage mineral in low-temperature hydrothermal veins cutting alkalic intrusive rocks in the differentiated alkalic massif. Associated minerals include zeolites and apophyllite (HOM).

In the Salmon River district near Riggins, Idaho county, Idaho, USA, zeophyllite has been found in spherical forms consisting of radiated crystal aggregates in dolostone. Pyrite, epidote and chlorite have also been introduced.
It appears that dolostone and a chlorite schist have been intruded by a granite pegmatite. Fluorine and water have traveled from the pegmatite into the dolostone and the schist. Tantalite-(Mn) was identified in fairly large specimens in the pegmatite and contains disseminated zeophyllite (AM 11.249-252)

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