Rock Identifier
Black Tourmaline in Quartz (Schorl tourmaline (NaFe3Al6(BO3)3Si6O18(OH)4) with quartz (SiO2), polished/carved) — mineral
mineral

Black Tourmaline in Quartz

Schorl tourmaline (NaFe3Al6(BO3)3Si6O18(OH)4) with quartz (SiO2), polished/carved

AI-generated identification · may be incorrect

Black, vitreous schorl contrasts with translucent-to-clear, glassy quartz; both are typically Mohs 7–7.5, with tourmaline’s prismatic/trigonal crystal structure and quartz’s hexagonal structure. The pictured piece is a polished, shaped specimen, possibly a pendant or decorative carving.

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Physical properties

Black, vitreous schorl contrasts with translucent-to-clear, glassy quartz; both are typically Mohs 7–7.5, with tourmaline’s prismatic/trigonal crystal structure and quartz’s hexagonal structure. The pictured piece is a polished, shaped specimen, possibly a pendant or decorative carving.

Formation & geological history

Tourmaline and quartz commonly crystallize together in granite pegmatites and hydrothermal veins during late igneous cooling, generally in Precambrian to younger host rocks. Major sources include Brazil, Afghanistan, Pakistan, Madagascar, Namibia, and the United States.

Uses & applications

Used as a mineral specimen, ornamental carving, and jewelry; quartz is also important in glass, electronics, and abrasives, while tourmaline is valued for its piezoelectric and pyroelectric properties.

Geological facts

Schorl is the most common black tourmaline and is iron-rich. Heating or rubbing tourmaline can produce an electric charge, attracting light particles.

Field identification & locations

Identify it by the opaque black tourmaline cap, translucent quartz body, strong hardness, and lack of metallic luster; a glass imitation may show bubbles and scratches more easily. Exact identification would benefit from magnification and testing.