igneous

Arfvedsonite in Quartz (also known as Eudialyte/Garnet Syenite variety)

Arfvedsonite [Na3(Fe2+)4Fe3+Si8O22(OH)2] within a silicate matrix

Hardness: 5-6 (Mohs scale); Color: Dark brown to black with pinkish-red or white inclusions; Luster: Vitreous to pearly; Crystal structure: Monoclinic; Cleavage: Good; Specific gravity: 3.44

Hardness: 5-6 (Mohs scale)
Color: Dark brown to black with pinkish-red or white inclusions
Luster: Vitreous to pearly

Identified March 28, 2026More igneous →

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Physical properties

Hardness: 5-6 (Mohs scale); Color: Dark brown to black with pinkish-red or white inclusions; Luster: Vitreous to pearly; Crystal structure: Monoclinic; Cleavage: Good; Specific gravity: 3.44

Formation & geological history

Formed in highly alkaline plutonic rocks, typically within nepheline syenites and granitic pegmatites. These specimens are often found in Precambrian geological formations.

Uses & applications

Primarily used for lapidary work, jewelry (pendants/beads), and as collectible metaphysical stones believed to aid in manifestation.

Geological facts

This specimen is often confused with Astrophyllite or Nuummite due to its dark appearance and internal flashes. It is a sodium-rich amphibole mineral named after the Swedish chemist Johan August Arfwedson.

Field identification & locations

Identify in the field by its association with alkaline igneous rocks and its distinct blueish or dark brown bladed crystals. Commonly found in Greenland (Ilimaussaq complex), Canada (Mont Saint-Hilaire), and Russia (Kola Peninsula).

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

Blue Apatite

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

mineral

Sodalite

Sodalite - Na8(Al6Si6O24)Cl2

mineral

Magnetite

Magnetite (Fe3O4)

mineral