Galena 1–2% silver, a byproduct that far outweighs the main lead ore in revenue. Galena deposits often also contain significant amounts of silver as included silver sulfide mineral phases or as limited solid solution within the galena structure. These argentiferous galenas have long been the most important ore of silver. Galena deposits are found worldwide in various environments. Noted deposits include those at Freiberg in Saxony; Cornwall, the Mendips in Somerset, Derbyshire, and Cumberland in England; the Madan and Rhodope Mountains in Bulgaria; the Sullivan Mine of British Columbia; Broken Hill and Mount Isa in Australia; and the ancient mines of
Mineral hydration Mineral hydration Mineral hydration is an inorganic chemical reaction where water is added to the crystal structure of a mineral, usually creating a new mineral, usually called a "hydrate". In geological terms, the process of mineral hydration is known as "retrograde alteration" and is a process occurring in retrograde metamorphism. It commonly accompanies metasomatism and is often a feature of wall rock alteration around ore bodies. Hydration of minerals occurs generally in concert with hydrothermal circulation which may be driven by tectonic or igneous activity. There are two main ways in which minerals hydrate. One is conversion of an oxide