igneous

Granite

Phaneritic Plutonic Rock (High Silica content)

Hardness: 6-7 on Mohs scale; Color: Grayish-white with salt and pepper speckling; Luster: Dull to vitreous; Crystal structure: Phaneritic (visible interlocking crystals of quartz, feldspar, and mica); Cleavage: None (fractures irregularly); Specific gravity: 2.65–2.75 g/cm³.

Hardness: 6-7 on Mohs scale
Color: Grayish-white with salt and pepper speckling
Luster: Dull to vitreous

Identified March 16, 2026More igneous →

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Physical properties

Formation & geological history

Formed from the slow cooling of magma deep beneath the Earth's surface (intrusive igneous). It can date back billions of years to the Archean Eon or be as young as a few million years. Typically found in continental crust and mountain ranges.

Uses & applications

Extensively used in construction (countertops, floor tiles, paving stones), monuments, and as crushed stone for road base. Sometimes used for low-cost lapidary tumbling for hobbyists.

Geological facts

Granite is the most common rock in Earth's continental crust. It is the primary component of many famous mountain ranges, including the Sierra Nevada and the Himalayas. Due to its durability, it was used to build the Great Pyramid of Giza's inner chambers.

Field identification & locations

Identify by its interlocking 'mosaic' of minerals and lack of layering. It will not react with acid (unlike limestone) and can easily scratch glass. Commonly found in mountainous regions or as glacial erratic stones in gravel pits.

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

Magnetite

Iron(II,III) oxide (Fe3O4)

mineral

Blue Apatite

Apatite (Group), Ca5(PO4)3(F,Cl,OH)

mineral

Sodalite

Sodalite - Na8(Al6Si6O24)Cl2

mineral

Magnetite

Magnetite (Fe3O4)

mineral