Formula: CaMg3(Al5Mg)(Si6O18)(BO3)3(OH)3F
Cyclosilicate (ring silicate), tourmaline group
Specific gravity: 2.97 to 3.14
Hardness: 7½
Streak: Light-brown, light-green, or white
Colour: Black, greenish-black, brownish-black, brown, green, colourless
Common impurities: Mn,Ti,Na,Cr,V,Zn,H2O

Metamorphic environments

Fluor-uvite is found in calcium-rich rocks subjected to contact metamorphism and the addition of boron. Associated minerals include apatite, calcite, dolomite, scapolite and tremolite (Mindat).


There are four co-type localities, Franklin, the Fowler quarry, the Franklin quarry and the franklin mine, all in the Franklin Mining District, Sussex county, New Jersey, USA.

At Gouverneur, St Lawrence county, New York, USA, fluor-uvite is relatively common and is the predominant tourmaline at the Bush farm. Crystals of fluor-uvite up to 14 cm have been found here (R&M 91-6.523-525).

At the The Selleck Road Tremolite and Tourmaline Locality, West Pierrepont, St. Lawrence County, New York, USA, fluor-uvite occurs as both single crystals and matrix specimens, up to 16 cm in size. Associated minerals include tremolite, calcite and phlogopite (R&M 91-2.116-131).

Back to Minerals