igneous

Basalt River Pebbles

Mafic Volcanic Rock (主要成分: SiO2, MgO, FeO)

Hardness: 6.0 on Mohs scale; Color: dark grey to black/brown; Luster: dull to earthy; Crystal structure: aphanitic (fine-grained); Specific gravity: 2.8-3.0.

Hardness: 6
Color: dark grey to black/brown
Luster: dull to earthy

Identified May 27, 2026More igneous →

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Physical properties

Hardness: 6.0 on Mohs scale; Color: dark grey to black/brown; Luster: dull to earthy; Crystal structure: aphanitic (fine-grained); Specific gravity: 2.8-3.0.

Formation & geological history

Formed from the rapid cooling of magnesium-rich and iron-rich lava at or near the Earth's surface. These specific specimens have been rounded and polished through fluvial transport (river action) or wave action.

Uses & applications

Used primarily in landscaping, aquarium decor, and aggregate for construction. High-quality basalt is used for stone massage therapy and decorative home accents.

Geological facts

Basalt is the most common rock type in the Earth's crust and makes up most of the ocean floor. It is juga found on the Moon and Mars.

Field identification & locations

Identify by its dark color, heavy weight relative to size, and fine-grained texture. Collected easily in riverbeds or volcanic coastal areas. Look for smoothness indicating water erosion.

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

Dalmatian Jasper

Aplite with Arfvedsonite inclusions

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