Goethite and lepidocrocite, both crystallizing in orthorhombic system, are the most common forms of iron(III) oxide-hydroxide and the most important mineral carriers of iron in soils.

• 针铁矿及鳞铁矿皆为斜方晶系的晶体；它们是氢氧化铁最常呈现的形式；也是铁在土壤中最重要的矿物媒介。