igneous
Basalt River Stone
Aphanitic Basalt
Hardness: 5-6 (Mohs); Color: Dark grey to black or dark brown; Luster: Dull/Earthy; Structure: Aphanitic (fine-grained); Specific Gravity: 2.8-3.0
- Hardness
- 5-6 (Mohs)
- Color
- Dark grey to black or dark brown
- Luster
- Dull/Earthy
Identified More igneous →
Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 5-6 (Mohs); Color: Dark grey to black or dark brown; Luster: Dull/Earthy; 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. Often rounded into smooth pebbles by water erosion in riverbeds or coastal areas.
Uses & applications
Used in landscaping, decorative stone, aquarium decor, hot stone massage therapy, and construction aggregate.
Geological facts
Basalt is the most common rock type in the Earth's crust and makes up most of the ocean floor. It is also found on the Moon and Mars.
Field identification & locations
Identify by its heavy weight (high density), dark matte color, and lack of visible crystals. It is commonly found in volcanic regions or transported to riverbanks.
More like this
Other igneous specimens
Granite
Granite
Igneous
Granite
Granite
Igneous
Blue Apatite
Fluorapatite (Ca5(PO4)3F)
mineral
Dalmatian Jasper
Aplite with Arfvedsonite inclusions
igneous
Magnetite
Iron(II,III) oxide (Fe3O4)
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