Oxycalcioroméite

oxycalcioromeite

derbylite

stibiotantalite

Nanyangshan

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Formula: Ca2Sb5+2O
Oxide, roméite group, pyrochlore supergroup, antimony-bearing mineral
Crystal System: Isometric
Specific gravity: 5.393 calculated
Streak: Pale yellow
Colour: Reddish brown
Luminescence: No fluorescence under UV
Environments

Pegmatites
Metamorphic environments

Oxycalcioromeite is a relatively new mineral, approved in 2012.

Localities

At the Nanyangshan pegmatite field, Lushi County, Sanmenxia, Henan, China, stibiotantalite occurs on the lithium - cesium - tantalum pegmatite, associated with oxystibiomicrolite, oxycalcioroméite, hydrokenomicrolite, hydroxynatromicrolite (not an approved mineral), hydromicrolite (not yet approved, February 2024), stibnite, bismuthinite, tantalite-(Mn), columbite-(Mn), spodumene, polylithionite, trilithionite, luanshiweiite, fluorluanshiweiite, elbaite, albite and quartz (CJMP 61.5.965–977).

At the type locality, the Buca della Vena Mine, Pontestazzemese, Stazzema, Lucca Province, Tuscany, Italy, oxycalcioroméite occurs as euhedral octahedra, up to 0.1 mm in size, embedded in dolostone lenses at the zoned baryte - pyrite - magnetite - hematite ore body at the contact between a metavolcanic-metasedimentary Triassic (252-201 million years ago) schist and dolostone and Lower Jurassic (201 to 175 million years ago) marble. The oxycalcioroméite crystallised from hydrothermal fluids related to Alpine metamorphism of greenschist facies. Associated minerals include calcite, cinnabar, derbylite, dolomite, hematite, mica, pyrite, sphalerite and tourmaline (MM 77.3027-3037).
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