mineral

Black tourmaline (schorl) on quartz matrix

Schorl, NaFe3Al6(BO3)3Si6O18(OH)4, commonly associated with quartz (SiO2)

AI-generated identification · may be incorrect

Black, strongly striated prismatic crystal with vitreous to submetallic luster; Mohs hardness 7–7.5, trigonal crystal structure, poor cleavage, and specific gravity about 3.1–3.3. The pale host appears to be massive quartz, with possible feldspar or mica.

Identified August 18, 2026More mineral →

Explore Black tourmaline (schorl) on quartz matrix in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

At a glance

Common name: Black tourmaline (schorl) on quartz matrix
Scientific name: Schorl, NaFe3Al6(BO3)3Si6O18(OH)4, commonly associated with quartz (SiO2)
Category: mineral
Identified: August 18, 2026
Method: Standard

AI Estimated Value

Approximately $30–$150 for a common mounted specimen; $200–$1,000+ for large, sharply terminated crystals with attractive matrix and provenance.

Not an official valuation

AI estimate for general interest only — not an appraisal. Actual value depends on condition, provenance, and market demand. Verify with a professional before buying, selling, or insuring.

This identification was generated by AI and may contain errors. Verify important details before relying on them — and never use an AI result to judge whether a specimen is safe to handle. Read the full disclaimer

Physical properties

Formation & geological history

Forms in boron-rich granitic pegmatites and hydrothermal veins as magma cools, commonly during the Precambrian to Mesozoic depending on locality. This specimen is mounted on a polished decorative base, likely resin or another processed material.

Uses & applications

Collected as a crystal specimen and used decoratively; tourmaline is also cut as a gemstone, while quartz matrix specimens are popular in mineral displays. Schorl is generally valued for aesthetics rather than jewelry transparency.

Geological facts

Tourmaline is piezoelectric and becomes electrically polarized when heated or compressed. The vertical striations and nearly opaque black color are characteristic of schorl.

Field identification & locations

Identify by its black color, elongated triangular-to-rounded prism, strong lengthwise striations, and hardness sufficient to scratch glass; quartz matrix is typically harder than steel but lacks tourmaline’s striations. Common sources include Brazil, Afghanistan, Pakistan, Madagascar, Namibia, and the United States.