Autunite
Daybreak Mine
Spokane, Washington
This specimen measures 5cm x 8cm
Autunite Ca(UO2)2(PO4)2.10-12H2O
Phosphate; hydrous phosphate of calcium and uranium, often with some barium and magnesium
Color and Luster: Lemon- to sulfur yellow, yellowish-green, green; pearly, subadamantine; streak yellowish
Hardness: 2-2.5
Cleavage: Perfect in one direction
Fracture: Flakes yellow
Crystals: Tetragonal; usually thin tabular, also foliated, scaly micaceous aggregates
Photo by Mary Sutherland
Descriptions taken from
The Audubon Society Field Guide to North American Rocks and Minerals