Autunite
Image: <bdi><a href="https://www.wikidata.org/wiki/Q56247090" class="extiw" title="d:Q56247090"><span title="mineral collector and dealer">Robert M. Lavinsky</span></a></bdi> (CC BY-SA 3.0)
Mineral NameAutunite
Chemical FormulaCa(UO₂)₂(PO₄)₂·10-12H₂O
Mohs Hardness2
Crystal Systemtetragonal
Lustervitreous
Streak Colorpale yellow
Cleavageperfect on {001}
Fractureuneven
Specific Gravity3.1
Colorslemon-yellow, greenish-yellow, bright green
Transparencytransparent
Type LocalityDaybreak Mine (Dahl lease), Mount Kit Carson, Spokane County, Washington, USA
Mineral GroupPhosphates
Usesminor ore of uranium, collector
Associated Mineralsuraninite, torbernite, meta-autunite, quartz
Rarityuncommon
Description
This specimen features a vibrant, apple-green to yellowish-green aggregate of platy, tabular crystals forming a radiating or stacked habit. The individual crystals exhibit a distinct micaceous or layered appearance, creating a textured, almost fan-like surface.
Geological Context
Autunite is a secondary uranium mineral that forms in the oxidized zone of uranium-bearing ore deposits, typically found in pegmatites or granitic rocks where primary uranium minerals have undergone alteration. Its presence is indicative of the weathering of primary uranium minerals.
