igneous

Granodiorite Core

Granodiorite

Hardness: 6-7 on Mohs scale. Color: Mottled salt-and-pepper (gray, white, pink, and black). Luster: Phaneritic (crystalline). Structure: Massive, granular. Specific gravity: 2.6-2.7.

Hardness: 6-7 on Mohs scale
Color: Mottled salt-and-pepper (gray, white, pink, and black)
Luster: Phaneritic (crystalline)

Identified April 6, 2026More igneous →

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Physical properties

Hardness: 6-7 on Mohs scale. Color: Mottled salt-and-pepper (gray, white, pink, and black). Luster: Phaneritic (crystalline). Structure: Massive, granular. Specific gravity: 2.6-2.7.

Formation & geological history

Formed by the slow cooling of silica-rich magma deep underground (plutonic). This specific specimen appears to be a drill core sample, likely pulled from bedrock during geological surveying or construction prep.

Uses & applications

Used in heavy construction, road building, and as dimension stone for countertops or monuments. Drill cores like this are used for site investigation and mineral exploration.

Geological facts

Granodiorite is the main component of the Sierra Nevada batholith in California. It is chemically intermediate between diorite and granite.

Field identification & locations

Identify by its circular, smooth sides indicative of diamond-tipped core drilling. Look for high quartz (>20%) and plagioclase feldspar. Common in mountainous regions with deep-seated tectonic activity.

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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