Syngenite

It was first described in 1872 for an occurrence as druse on halite in the Kalusa Salt deposit, Ivanovo-Frankovsk Oblast', Ukraine. The name is from Greek 'συγγενής' (related) due to its chemical similarity to polyhalite. It occurs in marine evaporite deposits as a diagenetic phase. It also forms as a volcanic sublimate, as vein fillings in geothermal fields and in caves where it is derived from bat guano. It occurs in association with halite and arcanite in salt deposits; and with biphosphammite, aphthitalite, monetite, whitlockite, uricite, brushite and gypsum in cave environments. It is also found in hardened cement which has relatively higher amount of potassium.