Granite

Hardness: 6-7 (Mohs), Color: Intergrown white/light-colored (quartz, feldspar) and black/dark-colored (biotite, amphibole) minerals, Luster: Vitreous to dull, Crystal structure: Granular, phaneritic (coarse-grained)

Formed from the slow crystallization of magma below the Earth's surface (intrusive igneous rock). This slow cooling allows for the formation of large, visible mineral grains. Typically forms in continental crust settings, often associated with orogenic (mountain-building) events. Geological age can vary widely, from Precambrian to Cenozoic, depending on the specific intrusion event.

Industry: Countertops, flooring, building facades, monuments, curbing, crushed stone for construction aggregate. Its durability and aesthetic appeal make it a popular choice. Jewelry: Not typically used for jewelry, but polished granite can be used for decorative items. Construction: Widely used as a dimension stone and aggregate.

Granite is one of the most common igneous rocks found in the continental crust. Its high quartz content makes it very durable and resistant to weathering. Many of the world's most impressive mountains and large geological formations are composed of granite. Famous examples include Mount Rushmore and Yosemite's Half Dome.

In the field, granite can be identified by its distinctive speckled appearance, showing intergrown light and dark minerals, and its coarse-grained texture. It feels hard and is difficult to scratch with a knife. It does not react with acid (unlike limestone). It is commonly found in large batholiths and laccoliths in mountainous regions, shield areas, and platforms on every continent. To collect, look for outcrops where erosion has exposed the rock, often in riverbeds, glacial tills, or road cuts. Confirm its identity by observing its mineral composition (quartz, feldspar, mica/amphibole) and its crystalline, granular texture.