Yellowcatite

yellowcatite

barnesite

gypsum

mandarinoite

Images

Formula: KNaFe3+2(Se4+O3)2(V5+2O7).7H2O
Hydrated vanadate, selenium-bearing mineral
Crystal system: Hexagonal
Specific gravity: 2.79 measured, 2.780 calculated
Hardness: 2
Streak: Pale yellow
Colour: Yellow
Luminescence: No fluorescence under long wave or short wave UV
Solubility: Insoluble in water and slowly soluble in dilute hydrochloric acid at room temperature
Environments

Sedimentary environments
Hydrothermal environments

Yellowcatite is a new mineral, approved in 2024 and pending publication (as of May 2025).

Localities

At the type locality, School Section 32; 22-22, Thompsons Mining District, Grand County, Utah, USA, yellowcatite was found as a post-mining mineral. It is named for the Yellow Cat Mesa and for the Yellow Cat Road located above the underground workings of the mine (AM 110.5.828).
The crystals are thin hexagonal plates, up to about 0.2 mm across. Yellowcatite is a secondary, post-mining phase occurring on montroseite - corvusite - asphaltite - mica -bearing sandstone. Associated minerals include barnesite, gypsum and mandarinoite (Mindat).
Yellowcatite from School Section 32 - Image

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