Obsidian and variations
Obsidian is the name given to volcanic glass – a rock rather than a mineral, it is a mixture of cryptocrystalline grains of silica minerals in a glass-like suspension and displays a conchoidal fracture. Obsidian forms during the last stage of volcanic activity, close to the earths surface cooling occurs too quickly for crystals to grow. Natural obsidian varieties include black, bluish, mahogany, gold & silver sheen, rainbow, etc. – the colours due largely to refraction by microscopic bubbles (and microscopic mineral inclusions such as magnetit in “Rainbow Obsidian”). Lustre: Vitreous
Although gem-quality water-clear coloured ‘obsidian’ does occasionally occur naturally, it is rare. Chemically and structurally the same as glass, it can be impossible to distinguish between natural and man-made material. With over 30 years in the industry we suspect that the large majority of these clear varieties of obsidian on the world market are in fact, artificial glass mass-produced in places such as Indonesia. Having said this, everything holds a resonance or vibration and these clear varieties remain extremely popular.