Rocks

naturally occurring solid aggregate of one or more minerals or mineraloids

rock formed by the deposition of material

Limonite () is an iron ore consisting of a mixture of hydrated iron(III) oxide-hydroxides in varying composition. The generic formula is frequently written as , although this is not entirely accurate as the ratio of oxide to hydroxide can vary quite widely. Limonite is one of the three principal iron ores, the others being hematite and magnetite, and has been mined for the production of iron since at least 400 BC.

thumb|This Balancing rock|balancing boulder, "[[Balanced Rock", stands in Garden of the Gods park in Colorado Springs, Colorado, United States.]] thumb|Boulder in British Columbia, Canada thumb|Kämmenkivi stone on the Pisa hill in Kuopio, Finland thumb|Balanced granite boulders at Hyderabad, India In geology, a boulder is a rock fragment with size greater than in diameter. Smaller pieces are called cobbles and pebbles. While a boulder may be small enough to move or roll manually, others are extremely massive. In common usage, a boulder is too large for a person to move. Smaller boulders are us

thumb|Outcrop of volcanic rock in Germany An outcrop or rocky outcrop is a visible exposure of bedrock or ancient superficial deposits on the surface of the Earth and other terrestrial planets.

thumb|Quartz-filled geode, shown from inside (top) and outside (bottom)

thumb|upright|Soil with broken rock fragments overlying bedrock at Reay|Sandside Bay, Caithness, Scotland thumb|Soil profile with bedrock labeled R

Geological phenomenon where rocks move and inscribe long tracks along a smooth valley floor without human or animal intervention

magmatic rock formed below the surface

A ventifact (also wind-faceted stone, windkanter) is a rock that has been abraded, pitted, etched, grooved, or polished by wind-driven sand or ice crystals. The word "Ventifact" is derived from the Latin word "Ventus" meaning 'wind'. These geomorphic features are most typically found in arid environments where there is little vegetation to interfere with aeolian particle transport, where there are frequently strong winds, and where there is a steady but not overwhelming supply of sand.

orange-yellow to black coating found on exposed rock surfaces in arid environments

breccia formed by tectonic forces

small grain size infilling material in fault mainly consisting of clay minerals

giant geode found in Spain near the town of Pulpí

thumb|right|Polished mohawkite nugget thumb|Mohawkite nugget

rock native to an area

old name for a large group of minerals, soap clays