igneous

Basalt with Quartz/Zeolite Inclusions

Porphyritic Basalt (SiO2 with Aluminosilicates)

Hardness: 5-7 on Mohs scale; Color: Black or dark grey groundmass with white/clear inclusions; Luster: Vitreous (crystals) to dull/earthy (matrix); Structure: Aphanitic to porphyritic; Cleavage: None to poor.

Hardness: 5-7 on Mohs scale
Color: Black or dark grey groundmass with white/clear inclusions
Luster: Vitreous (crystals) to dull/earthy (matrix)

Identified March 16, 2026More igneous →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Formed from the rapid cooling of magnesium-rich and iron-rich lava at or near the Earth's surface. The white crystals represent minerals that grew earlier in the magma chamber or secondary minerals filling vesicles (gas bubbles) after the lava cooled.

Uses & applications

Primarily used in construction as aggregate or road base in its bulk form; smaller decorative pieces are used in aquarium gravel, landscaping, or as introductory collector specimens.

Geological facts

Basalt is the most common rock in the Earth's crust and makes up most of the ocean floor. The white inclusions in specimens like this one often provide a record of different cooling stages or later hydrothermal activity.

Field identification & locations

Identify by its dark, heavy fine-grained matrix and the high contrast of the white crystal inclusions. Commonly found in volcanic regions, coastal beaches near basaltic flows, and riverbeds. Collectors look for high contrast and clear crystal shapes.

Other igneous specimens

See all

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