igneous

Basalt with Quartz/Calcite Veins

Basalt (Aphanitic Mafic Igneous Rock)

Hardness: 6 (matrix), 7 (veins); Color: Dark grey to black with white linear inclusions; Luster: Dull/earthy for the rock, vitreous for the veins; Structure: Fine-grained/aphanitic; Specific Gravity: 2.8 - 3.0

Hardness: 6 (matrix), 7 (veins)
Color: Dark grey to black with white linear inclusions
Luster: Dull/earthy for the rock, vitreous for the veins

Identified March 29, 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 the surface. The white veins are secondary hydrothermal deposits where minerals like quartz or calcite filled fractures in the rock long after initial cooling.

Uses & applications

Predominantly used as crushed stone for road base, concrete aggregate, and railroad ballast. Small water-worn specimens like this are often kept as part of beach-combing collections or used in rock tumblers.

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 extensively on the Moon and Mars.

Field identification & locations

Identify by its dark, dense matrix and heavy weight relative to size. Found globally in volcanic regions and on beaches where glacial or river transport has deposited them. Collectors look for the unique patterns created by 'X' or 'cross' shaped 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