What is Kieserite?
Kieserite is a hydrated magnesium sulfate of evaporite deposits, an important potash-associated mineral and a clear example of water-bearing crystal chemistry.
Mineralogy and crystal structure
Reference formula: MgSO4·H2O. Kieserite has a monoclinic structure with one water molecule per magnesium sulfate unit. It can transform during hydration, so reported specimens should be stored with humidity and alteration history in mind. Kieserite is classified with sulfates and has a monoclinic crystal system. Typical hardness is 2.5–3 on the Mohs scale and specific gravity is approximately 2.5–2.6.
Colour, lustre and habit
Typical colours include colourless, white, grey, yellowish. The usual granular, tabular, massive habit and vitreous, pearly lustre help describe a specimen, but colour alone is not diagnostic.
Formation and notable localities
Kieserite forms in or is associated with marine evaporites, salt domes and potassium-magnesium sulfate deposits. Important documented localities include Germany, Spain, Russia, Kazakhstan, Canada and the United States.
A clean, modern study specimen
Kieserite is ideal for collectors who like minerals with a direct link to both geology and industry. Its restrained colour lets the label, crystal structure and evaporite setting carry the story, making it a strong addition to a systematic cabinet.
Collecting and care
Store sealed and dry; avoid water, high humidity and aggressive cleaning because the mineral can hydrate or dissolve.
