Stones

Stones are naturally occurring solid aggregates composed of minerals or mineraloids. In geology, the term is often used for a piece of rock that is large enough to handle or use for a specific purpose. Stones arise from three broad geological histories: sedimentary stones formed by cementation of mineral sediments; igneous stones formed by solidification of molten rock; and metamorphic stones formed by alteration of existing rocks under heat and pressure.

Common examples include sedimentary stones such as limestone, sandstone, and shale; igneous stones such as granite, basalt, and obsidian; and metamorphic stones such as marble, slate, and quartzite. Stones vary in hardness, density, porosity, grain size, and color, factors that influence their durability and suitability for different tasks.

Stones are quarried from natural deposits and then cut, shaped, and finished for use in construction, sculpture, tools, and decorative objects. In architecture and engineering, stone has historically been valued for strength and longevity; carved and polished stones are used for monuments and aesthetic features. Some stones, including flint and obsidian, have been used to fashion cutting tools and weapons.

Stones also hold cultural and historical significance. The Rosetta Stone, a granodioritic stele dating to ancient Egypt, provided key inscriptions that aided decipherment of hieroglyphs. Geologists study stones to understand Earth history, including past environments and tectonic activity. Environmental concerns related to stone extraction include landscape disruption and quarrying waste.