mineral

Tourmalinated quartz

Quartz (SiO₂) with black tourmaline (schorl; NaFe²⁺₃Al₆(BO₃)₃Si₆O₁₈(OH)₄) inclusions

AI-generated identification · may be incorrect

Hardness: quartz 7, tourmaline 7–7.5 Mohs; transparent to translucent gray-brown quartz with vitreous luster and black, prismatic tourmaline crystals. Quartz is trigonal with no cleavage; tourmaline is trigonal and has poor cleavage.

Hardness: quartz 7, tourmaline 7–7

Identified September 16, 2026More mineral →

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Physical properties

Formation & geological history

Forms in hydrothermal quartz veins and granitic pegmatites when tourmaline grows inside quartz during late-stage cooling, commonly in the Mesozoic to Precambrian geologic record.

Uses & applications

Used as a decorative and lapidary material, especially in cabochons, polished slices, and collectible mineral specimens; transparent pieces may be set in jewelry.

Geological facts

The dark needles are typically schorl, the most common black tourmaline. Tourmaline is piezoelectric and can develop electrical charge when heated or compressed.

Field identification & locations

Identify it by glassy quartz enclosing sharply contrasting black, elongated tourmaline crystals; distinguish it from smoky quartz by the visible inclusions. Common sources include Brazil, Madagascar, Pakistan, Afghanistan, and the United States.