Specific gravity: 3.19(2) measured, 3.200 calculated for the empirical formula and 3.263 calculated for the ideal formula
Colour: Very dark brown, appearing black
Mikehowardite is a new mineral, approved in 2020 and to date (June 2022) reported only from the type
At the type locality, the North Wilson pit, Union Carbide Mine, Wilson Springs, Garland county, Arkansas, USA, two new secondary minerals, mikehowardite and donowensite, have been found intimately associated with each other, and formed by the oxidation of primary ore vanadium minerals contained in altered sedimentary rocks adjacent to their contact with a syenite intrusion. The crystals of mikehowardite are equant prisms, up to about 0.15 mm in diameter, with slightly sloping terminations (CM 60.543-554).
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