Arfvedsonite

Arfvedsonite is a striking, dark mineral belonging to the amphibole group, commonly found in shades ranging from deep black to dark blue, often with subtle greenish or bluish iridescence. This mineral forms in large, prismatic, or needle-like crystals that are highly lustrous and reflective. Arfvedsonite is primarily composed of sodium, iron, and silicate, and is typically found in igneous rock formations, particularly in alkaline environments such as nepheline syenites and other silica-undersaturated rocks.