Limonite is a hydrous iron hydoxy-oxide: FeO·OH·nH2O. It has a nonmetallic, earthy luster, yellowish-brown to orangish-brown color & streak, and ranges in hardness from about 1 to 6. Many limonite samples are powdery, amorphous (shapeless) masses with an earthy feel.
Limonite - soft limonite (left, 2.5 cm across) & hard limonite (right, 5.0 cm across).
Limonite-goethite-hematite (yellow-brown-red) (5.0 cm across) - a differentially-eroded iron oxide crust (derived from an irregularly rounded concretion) having all three major iron oxide minerals mixed together.