Goethite

Goethite is a mineral composed of iron oxyhydroxide (FeO(OH)), belonging to the oxide group. It occurs as acicular crystals, botryoidal masses, or concretions, with a color ranging from dark brown to black, sometimes with iridescent reflections.

Formed in the alteration zones of iron-rich deposits, it is often associated with hematite, limonite, or quartz. The most beautiful specimens are prized for their elegant crystalline forms, radiating aggregates, and astonishing natural iridescence.