Formula: V4+O(SO4).5H2O
Hydrated sulphate, minasragrite group, orthorhombic paramorph of monoclinic minasragrite, vanadium-bearing mineral
Crystal System: Orthorhombic
Specific gravity: 2 calculated
Hardness: 1
Streak: Pale blue
Colour: Blue

Sedimentary environments
Hydrothermal environments

Orthominasragrite occurs as a secondary mineral in sediment-hosted uranium-vanadium ore deposits (Webmin).


At the type locality, the North Mesa Mine group, Temple Mountain, San Rafael Mining District, Emery county, Utah, USA, the host rock is conglomerate. Orthominasragrite was found as pale to bright blue aggregates of grains in a silicified tree, which has a rim of coal 6–25 mm thick around it. Pyrite has replaced part of the tree, and groundwater has reacted with the pyrite to produce various iron sulphate minerals, accompanied by microscopic yellow crystals and aggregates of native sulphur. The iron sulphates generally occur in the outer rim of the coal and in the adjacent conglomerate. Material in the silicified tree is the probable source of the vanadium that occurs in blue and green secondary vanadium sulphate minerals, including orthominasragrite and minasragrite. Droplets of an ironvanadium-rich liquid are, in some cases, present on fractures in freshly exposed tree fragments. This liquid is acidic, destroying paper containers, and seeps from fractures to evaporate and form vanadium sulphate minerals, including orthominasragrite (CM 39.1325-1331). Associated minerals include minasragrite, pyrite, szomolnokite, kornelite, ferricopiapite, rozenite, montroseite and sulphur (HOM).

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