Mineral Guide · Mineral
Jachymovite is a rare hydrated uranium sulfate from the oxidised zones of uranium deposits, prized for its vivid yellow-green colour and locality history.
Jachymovite is a rare hydrated uranium sulfate from the oxidised zones of uranium deposits, prized for its vivid yellow-green colour and locality history.
Reference formula: (UO2)8(SO4)(OH)14·13H2O. Jachymovite is a highly hydrated uranyl sulfate. Its bright colour is attractive, but radioactivity and dehydration make provenance, sealed display and careful handling essential. Jachymovite is classified with sulfates and has a monoclinic crystal system. Typical hardness is 2–3 on the Mohs scale and specific gravity is approximately 3.3–3.5.
Typical colours include yellow, yellow-green, green, brown. The usual crusty, fibrous, earthy habit and vitreous, pearly lustre help describe a specimen, but colour alone is not diagnostic.
Jachymovite forms in or is associated with oxidised uranium veins and mine workings. Important documented localities include Jáchymov in the Czech Republic, Germany, France and other uranium districts.
Jachymovite is a specialist cabinet mineral rather than a casual jewellery stone. Its saturated yellow-green crusts and connection with the historic Jáchymov mining district give a curated mineral collection an immediate scientific and historical focus.
In modern symbolic language, yellow-green minerals are often associated with renewal and curiosity. These are cultural interpretations only; Jachymovite is a radioactive mineral and should be appreciated through responsible collecting and mineralogical study.
Radioactive and fragile: keep it labelled, sealed from dust, away from living areas, and handle only with appropriate radiation-safety guidance.
Reviewed by NotOnlyRocks Editorial Team
Last reviewed: 25 August 2026
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