igneous

Sodalite in Matrix (often called Blue Marble or Sodalite-Syenite)

Sodalite-bearing Syenite / Na8Al6Si6O24Cl2 (Sodalite component)

Hardness: 5.5 to 6 on Mohs scale; Color: White to grey matrix with distinct royal blue or lavender-blue patches; Luster: Vitreous to greasy; Crystal structure: Cubic (isometric) for sodalite; Cleavage: Poor; Specific gravity: 2.14 to 2.4

Hardness: 5
Luster: Vitreous to greasy

Identified March 16, 2026More igneous →

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Physical properties

Formation & geological history

Formed in silica-poor igneous rocks (alkaline rocks) such as nepheline syenites and pegmatites. It crystallizes from late-stage sodium-rich hydrothermal fluids. Usually Proterozoic to Phanerozoic in age.

Uses & applications

Used primarily for lapidary work, cabochons, beads, ornamental carvings, and architectural accents like tabletops or tiles. It is a popular collector's mineral due to its vibrant color.

Geological facts

Sodalite is often mistaken for Lapis Lazuli, but it lacks the gold-colored pyrite specks characteristic of Lapis. Many specimens exhibit fluorescence, glowing orange or yellow under long-wave UV light.

Field identification & locations

Identify in the field by its rich blue color and association with white feldspars/nepheline. Found commonly in Brazil, Canada (Bancroft, Ontario), Namibia, and Russia. Look for the absence of metallic flecks to distinguish from Lapis.

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

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