igneous

Basalt with Quartz Veins

Amygdaloidal Basalt (matrix) with Crystalline SiO2 (veins)

Hardness: 6-7 (Mohs); Color: Dark grey to charcoal matrix with white/off-white banding; Luster: Dull/Earthy matrix with Vitreous veins; Structure: Fine-grained/Aphanitic igneous rock with secondary vein filling; Specific Gravity: 2.8 - 3.0

Hardness: 6-7 (Mohs)
Color: Dark grey to charcoal matrix with white/off-white banding
Luster: Dull/Earthy matrix with Vitreous veins

Identified March 24, 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 through the rapid cooling of basaltic lava at the Earth's surface. The veins were created much later when hydrothermal fluids rich in silica circulated through cracks and fractures in the cooling rock, precipitating quartz.

Uses & applications

Common basalt is used extensively in construction as aggregate, road base, and railroad ballast. This specific water-worn specimen is a 'river rock' often used in landscaping or as a basic pocket stone for beginning collectors.

Geological facts

The dark 'stripes' or veins in rocks like this are often referred to as 'wishing stones' in folklore, especially if the white line forms a continuous circle around the stone. Basalt is the most common rock type in the Earth's crust, making up most of the ocean floor.

Field identification & locations

Identify in the field by looking for heavy, dark, fine-grained rocks with contrasting white lines. Commonly found in riverbeds, glacial tills, and along coastlines where volcanic activity once occurred. They are excellent for tumbling to show the contrast between the dark host rock and light veins.

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

Sodalite

Sodalite - Na8(Al6Si6O24)Cl2

mineral

Blue Apatite

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

mineral

Magnetite

Magnetite (Fe3O4)

mineral