Uvite

uvite

tremolite

phlogopite

scapolite

Images

Formula: CaMg3(Al5Mg)(Si6O18)(BO3)3(OH)3(OH)
Cyclosilicate (ring silicate), tourmaline group, forms a series with feruvite (Mindat), only limited solid solution with liddicoatite, but complete solid solution series with dravite (Lapis 3.11,23)
Specific gravity: 2.96 to 3.06
Hardness: 7½
Streak: Light brown
Colour: Yellowish brown, brown, blackish brown, bluish black
Environments:

Metamorphic environments

Uvite occurs typically in calcium-rich rocks subjected to contact metamorphism and metasomatic processes which add boron (HOM); it is frequently found in marble associated with diopside, tremolite, phlogopite or meonite, sometimes with quartz (Dana, Lapis 3.23). Other associates include calcite, dolomite and apatite (HOM).

Localities

The type locality is the Facciatoia quarry, San Piero in Campo, Campo nell'Elba, Livorno Province, Tuscany, Italy.

At Newcomb, Essex county, New York, USA, uvite occurs as short prismatic crystals to 10 cm or as angular anhedral fragments embedded in albite. In some specimens it has a rim of rossmanite and/or olenite.
The following model for this mineral association is suggested:
(1) Grenville-age metamorphism: uvite, diopside, scapolite, graphite and phlogopite
(2) fracturing followed by invasion of aluminum- and silica-rich fluids that reacted with uvite to form rossmanite and/or olenite; the fluids became Na-rich toward the end of this stage and deposited albite and quartz.
(3) low-temperature alteration of diopside and scapolite to form tremolite (R&M 84.4.366).

Amity, Town of Warwick, Orange county, New York, USA, is an area of granite intrusions into marble and associated gneiss. The marble is mostly composed of white crystalline calcite that often has small flakes or spheres of graphite and phlogopite. Uvite/fluor-uvite occurs in marble as brown crystals to 5 cm. It is often fluorescent a creamy yellow colour (R&M 96.5.441).

At the Yellow Lake south roadcut, St. Lawrence County, New York, USA, uvite occurs as small crystals and crystal fragments embedded in or on quartz. It also occurs with graphite in the surrounding marble (R&M 86.4.356).

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