igneous

Granite

Granite (phaneritic felsic intrusive rock)

Hardness: 6-7 on Mohs scale. Color: Salt-and-pepper (gray, white, black, with some tan/brown weathering). Luster: Dull to vitreous depends on mineral face. Crystal structure: Phaneritic (visible crystals of quartz, feldspar, and biotite). Cleavage: Varies by mineral component.

Hardness: 6-7 on Mohs scale
Luster: Dull to vitreous depends on mineral face

Identified May 29, 2026More igneous →

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Physical properties

Formation & geological history

Formed from the slow crystallization of magma below Earth's surface. High in silica and alkali oxides. This specific specimen shows signs of secondary mineral veining (likely quartz) and iron oxide staining from environmental weathering.

Uses & applications

Widely used in construction for dimension stone, countertops, floor tiles, and as crushed stone for road base. Its durability makes it ideal for monuments and memorials.

Geological facts

Granite makes up a large part of the Earth's continental crust. Unlike oceanic crust which is primarily basalt, the continents 'float' because granite is less dense. The white vein running through this sample represents a later-stage hydrothermal injection where mineral-rich water filled a fracture.

Field identification & locations

Identify by its interlocking granular texture where crystals are visible to the naked eye. Look for the 'salt and pepper' appearance. Common globally in mountain ranges and shields. Collectors look for unique inclusions or large 'megacrysts' of feldspar.

Other igneous specimens

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Blue Apatite

Fluorapatite (Ca5(PO4)3F)

mineral

Dark Igneous Rock (Likely Basalt or Diabase)

Basalt (extrusive igneous rock) or Diabase (intrusive igneous rock - also known as Dolerite), largely composed of plagioclase feldspar, pyroxene (augite), and sometimes olivine and amphibole. Exact mineralogy would require thin section analysis.

Igneous