Tungstite is a hydrous

tungsten Tungsten, or wolfram, is a chemical element with the symbol W and atomic number 74. Tungsten is a rare metal found naturally on Earth almost exclusively as compounds with other elements. It was identified as a new element in 1781 and first isolat ...

oxide An oxide () is a chemical compound that contains at least one oxygen atom and one other element in its chemical formula. "Oxide" itself is the dianion of oxygen, an O2– (molecular) ion. with oxygen in the oxidation state of −2. Most of the E ...

mineral with formula: W O₃· H₂O. It is a secondary mineral formed by the

weathering Weathering is the deterioration of rocks, soils and minerals as well as wood and artificial materials through contact with water, atmospheric gases, and biological organisms. Weathering occurs ''in situ'' (on site, with little or no movement), ...

of other tungsten containing minerals. It crystallizes in the

orthorhombic In crystallography, the orthorhombic crystal system is one of the 7 crystal systems. Orthorhombic lattices result from stretching a cubic lattice along two of its orthogonal pairs by two different factors, resulting in a rectangular prism with a r ...

system in translucent yellow to yellow green masses. It is clay-like with

Mohs hardness The Mohs scale of mineral hardness () is a qualitative ordinal scale, from 1 to 10, characterizing scratch resistance of various minerals through the ability of harder material to scratch softer material. The scale was introduced in 1812 by th ...

of 2.5 and a

specific gravity Relative density, or specific gravity, is the ratio of the density (mass of a unit volume) of a substance to the density of a given reference material. Specific gravity for liquids is nearly always measured with respect to water (molecule), wa ...

of 5.5. It was first described in 1868 for an occurrence near

Trumbull, Connecticut Trumbull is a town located in Fairfield County, Connecticut, United States. It borders on the cities of Bridgeport and Shelton and the towns of Stratford, Fairfield, Easton and Monroe. The population was 36,827 during the 2020 census. Trumbul ...

at the Hubbard Tungsten Mine at Long Hill.

References

Mindat with location dataWebmineral Handbook of mineralogy
Tungsten minerals Hydroxide minerals Trumbull, Connecticut Orthorhombic minerals Minerals in space group 62 {{oxide-mineral-stub