What is Schorl?
Schorl is the black iron-rich tourmaline species, prized for striated prismatic crystals, pegmatite specimens and durable dark jewellery material.
Mineralogy and crystal structure
Reference formula: NaFe3Al6(BO3)3Si6O18(OH)4. Schorl is trigonal and belongs to the tourmaline supergroup. The black colour reflects iron-rich chemistry; it is a species, not merely a colour name for every dark tourmaline. Schorl is classified with silicates and has a trigonal crystal system. Typical hardness is 7–7.5 on the Mohs scale and specific gravity is approximately 3.0–3.3.
Colour, lustre and habit
Typical colours include black, brown-black, greenish black. The usual prismatic, striated, radiating habit and vitreous, pearly lustre help describe a specimen, but colour alone is not diagnostic.
Formation and notable localities
Schorl forms in or is associated with granitic pegmatites, hydrothermal veins, schists and metamorphic rocks. Important documented localities include Brazil, Afghanistan, Pakistan, Madagascar, Namibia, the United States and Europe.
The graphic black tourmaline species
Schorl sells through strong geometry and contrast. Long striated prisms look architectural in a pegmatite, while polished black material offers a durable and recognisable jewellery surface.
Collecting and care
Protect terminations from impact and clean with mild water. Avoid harsh heat and retain the matrix and locality for fine crystals.
