Home > Mexico IV Ojuela II – January 19 > MS1741 Goethite casts of Calcite with Malachite

Goethite casts of Calcite with Malachite - Sold


Goethite is an iron oxide hydroxide mineral, with the same crystal structure as diaspore. Lenz (1806) named the species after German poet, novelist, natural historian, and civil servant Johann Wolfgang von Goethe (1749-1832).

Goethite here forms casts of discoidal calcite. Oxidation of primary ores produces acidic waters which dissolve host limestone. This creates open space for crystals, including some crystals which we infer as discoidal calcite. Later fluids deposited goethite which hints at their form. Subsequently the discoidal calcite dissolved away, leaving hollow casts later infiltrated by additional goethite, calcite, and malachite. An interesting pseudomorph for the locality.