Black Tourmaline (Schorl)

Hardness: 7-7.5 (Mohs), Color: Opaque black, Luster: Vitreous to resinous, Crystal structure: Trigonal (often columnar or acicular crystals, but this specimen is shaped), Cleavage: Indistinct, Specific gravity: 3.06-3.26.

Formed in igneous and metamorphic rocks, particularly in granites, granite pegmatites, and high-temperature hydrothermal veins. It also occurs in sedimentary rocks as detrital grains due to its resistance to weathering. Geological age varies widely depending on the specific formation.

Used as a gemstone (though typically less valued than other tourmaline varieties due to its opacity), in electrical and pressure gauges (due to its piezoelectric properties), as a popular metaphysical stone for protection, and as a mineral specimen for collectors. The spherical shape indicates it has been cut and polished for ornamental or metaphysical use.

Black tourmaline, or Schorl, is the most common variety of tourmaline and accounts for about 95% of all natural tourmaline. Its intense black color is due to a high iron content. It is known for its strong electrical properties; it becomes electrically charged when heated or put under pressure.

In the field, black tourmaline often appears as elongated, prismatic crystals with vertical striations, frequently with a triangular cross-section. Its black color and hardness are key identifiers. It's commonly found in Brazil, Pakistan, Africa (e.g., Namibia, Tanzania), and the USA (e.g., Maine, California). For collectors, its raw crystal forms are sought after, and polished forms like the sphere in the image are popular for decorative and metaphysical purposes.