igneous

Granite with Quartz Vein

Phaneritic Felsic Igneous Rock (composed of Quartz [SiO2], Feldspar, and Mica)

Hardness: 6-7 on Mohs scale; Color: Mottled grey, black, and white with a pinkish/white crystalline quartz vein; Luster: Vitreous to pearly; Crystal structure: Phaneritic (visible coarse-grained crystals); Cleavage: Poor; Specific gravity: 2.6-2.7 g/cm³.

Hardness: 6-7 on Mohs scale
Luster: Vitreous to pearly

Identified March 27, 2026More igneous →

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Physical properties

Formation & geological history

Formed from the slow cooling and solidification of molten magma beneath the Earth's surface during the Precambrian to Cenozoic eras. The central vein formed via hydrothermal activity where mineral-rich hot water filled a fracture in the cooling rock.

Uses & applications

Used widely in construction (countertops, flooring, monuments), as crushed stone for road base, and as decorative landscaping or specimen collecting.

Geological facts

Granite makes up a large portion of the Earth's continental crust. The veins, like the one seen here, often serve as 'geological clocks' or indicators of volcanic and tectonic movement that occurred after the host rock solidified.

Field identification & locations

Identify in the field by its speckled 'salt and pepper' appearance and large, interlocking crystals. Commonly found in mountainous regions or shield areas like the Canadian Shield or the Appalachians. Collectors look for unique vein patterns or large crystal formations.

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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)

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Sodalite

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Blue Apatite

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

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Magnetite

Magnetite (Fe3O4)

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