Goethite
Image: <a href="//commons.wikimedia.org/wiki/User:Islam90" title="User:Islam90">Islam90</a> (CC BY-SA 4.0)
Mineral NameGoethite
Chemical FormulaFeO(OH)
Mohs Hardness5
Crystal Systemorthorhombic
Lusteradamantine
Streak Coloryellowish-brown
Cleavageperfect on {010}
Fractureuneven
Specific Gravity3.3
Colorsyellow, brown, reddish-brown, black
Transparencyopaque
Type LocalitySiegen, North Rhine-Westphalia, Germany
Mineral GroupOxides/Hydroxides
Usesiron ore, pigment, collector
Associated Mineralshematite, lepidocrocite, quartz, calcite
Raritycommon
Description
The image displays a microscopic view of goethite, showing layered and somewhat fibrous textures in shades of grey and brown. Macroscopically, it often appears as dark brown to black botryoidal, stalactitic, or massive aggregates.
Geological Context
Goethite is a widespread secondary mineral formed through the weathering of iron-rich minerals, commonly found in the oxidized zones of ore deposits, bogs, and as a major component of lateritic soils and limonite iron ores.
