What is Zippeite?
Zippeite is a bright yellow to orange hydrated uranyl sulfate, a secondary mineral formed where uranium ores react with acidic sulfate-rich solutions.
Mineralogy and structure
Reference formula: K2(UO2)6(SO4)3O2(OH)6·3H2O. Zippeite is monoclinic and chemically variable because its interlayer water and alkali content can change. The Guide gives a representative end-member formula and a labelled COD structure rather than false precision. Zippeite is classified with sulfates and has monoclinic crystal symmetry. Typical hardness is 2–3 on the Mohs scale and specific gravity is approximately 3.6–4.0.
Colour, lustre and habit
Typical colours include yellow, orange, yellow-green, brownish yellow. The usual crusty, tabular, powdery habit and vitreous, pearly, dull lustre help describe a specimen, but colour alone is not diagnostic.
Formation and notable localities
Zippeite forms in or is associated with oxidised uranium deposits, mine walls and sulfate-rich secondary cavities. Important documented localities include the Czech Republic, Germany, the United States, France, Portugal and Australia.
A yellow sulfate film with a uranium story
Zippeite often forms delicate crusts rather than large crystals, but the colour and chemistry are exceptional. A secure, well-documented micro-specimen can be more desirable than a larger anonymous coating.
Collecting and care
Radioactive and very soft: keep sealed and dry, avoid dust and direct handling, and follow radiation-safety procedures. Do not expose to heat or water.
