Granite

Hardness: 6-7 on Mohs scale. Color: Highly variable, typically light-colored (white, gray, pink, reddish) with dark mineral specks. Luster: Vitreous to sub-vitreous. Crystal structure: Phaneritic (coarse-grained, clearly visible crystals). No distinct cleavage planes for the rock as a whole, but individual mineral components may show cleavage. Specific gravity: 2.6-2.7 g/cm³. Fracture: Irregular to conchoidal.

Granite forms from the slow crystallization of magma beneath the Earth's surface (intrusive). The slow cooling allows large, interlocking mineral grains to develop. It is typically associated with continental crust formation and orogenic (mountain-building) events. Geological age varies greatly, from Precambrian to Cenozoic, depending on the specific intrusion event.

Granite is widely used as a building material for countertops, floor tiles, paving, monuments, and curbing due to its durability, aesthetic appeal, and ability to take a high polish. It is also used as crushed stone in construction aggregates. Historically, it has been used in major architectural projects.

Granite is one of the most common intrusive igneous rocks and forms the core of many mountain ranges. The term 'granite' is often used broadly to include a variety of coarse-grained felsic intrusive rocks. The exact mineral composition can classify it more specifically (e.g., granodiorite, quartz monzonite). The color variation in granite is primarily due to the type and abundance of feldspar (e.g., pink orthoclase, white plagioclase) and the presence of darker minerals like biotite and hornblende.

In the field, granite is identified by its coarse-grained texture (minerals are visible to the naked eye), the presence of quartz (typically glassy and gray/translucent), feldspars (often white, pink, or gray and opaque), and dark minerals like biotite mica (black, flaky) or hornblende (dark green to black, prismatic). It often forms large, massive outcrops. It is found on every continent, particularly in shield areas, mountain belts, and the cores of continents. Tips for collectors: Look for fresh exposures in road cuts, quarries, or glaciated areas where rocks are less weathered. Note the overall color and the individual mineral grains.