Class : Sulphates, chromates, molybdates
    Subclass : Hydrated sulphates
    Crystal system : Monoclinic
    Chemistry : MgFe(SO₄)₂OH 7H₂O
    Rarity : Uncommon

Botryogen is a rather uncommon double sulphate of magnesium and iron, formed by the alteration of iron sulfides, especially in arid climates. Its name comes from the Greek botrus (cluster) and gennân (to generate) in allusion to the botryoidal shape of the discovery samples. It is part of a classic mineralogical procession to which other iron sulphates commonly belong (copiapite, jarosite, amarantite, fibroferrite, etc...), resulting like it from precipitation from "natural" sulfuric acid formed by reaction of surface water with iron sulphides. By changing the conditions of the environment (temperature, pH, oxidation-reduction potential) these sulphates are easily hydrolyzed into ferric hydroxides (goethite, limonite, etc...). Botryogen occurs mainly in botryoidal or reniform masses, in spherolites with a radiated texture, rarely in small striated prismatic crystals. Its color is light to dark orange-red.

Main photo : Botryogen from Fallun, Dalarna, Sweden © Peter Haas

No known twin for this mineral species.

No fake inventories for this mineral species.