A mineral of the triclinic crystal system consisting of a hydrated sulphate of potassium, calcium, and magnesium, K2Ca2Mg(SO4)4, and usually…

A hydrated basic sulphate of iron and magnesium, now regarded as identical with botryogen.

An iron-containing mineral which occurs as rust-brown to yellow crystals, typically as an oxidation product of pyrite.

Hydrous chlorosulphate of magnesium and potassium, found esp. in Germany and Russia, largely used as a fertilizer.

A mineral now regarded as identical with polyhalite.

An iron aluminosulphate mineral of uncertain identity, described from microscopic yellow crystals found in southern Germany.

An iron-containing mineral belonging to the halotrichite group, typically occurring as fibrous masses of a white, yellowish, or purple colour.

Hydrous sulphate of chromium, iron, and aluminum, of a greenish-yellow colour.

A hydrous chloride and sulphate of mercury and ammonia, occurring as transparent or translucent crystals of a yellow to orange colour.

A cubic hydrated nitrogen compound of mercury (chemically, a salt of Millon's base) which occurs as yellow crystals and has the formula Hg2NX.H2O…

A rare mineral formed by the burning of copper pyrites in a mine and occurring as blue transparent crusts and radiating tufts of acicular crystals.

A hydrated sulphate of potassium, calcium, and copper found as transparent, pale blue to greenish blue, triclinic crystals at Chuquicamata, Chile.

Hydrated calcium ammonium sulphate, (NH4)2Ca(SO4)2·H2O, occurring in acicular monoclinic crystals and identical with artificial ammonium syngenite.