Black Tourmaline (Schorl)

Hardness: 7-7.5 (Mohs scale), Color: Opaque black, sometimes with a bluish or greenish tint. Luster: Vitreous to resinous. Crystal structure: Trigonal; often found in prismatic crystals with vertical striations, but this specimen appears tumbled. Cleavage: Indistinct. Specific Gravity: 3.0-3.2

Black tourmaline forms in igneous and metamorphic rocks, particularly granite and pegmatites, as well as in some hydrothermal veins. It crystallizes from magma or hydrothermal fluids rich in boron. Its formation often occurs during the late stages of magmatic differentiation or during regional metamorphism. Geological age varies widely depending on the specific deposit.

Industry: Used as a pressure sensor in electronic devices (piezoelectric properties). Jewelry: Polished and faceted for rings, pendants, and other adornments. Collecting Value: Valued by mineral collectors for its crystal habit and aesthetic appeal. Metaphysical: Believed by some to offer protection and grounding.

Black tourmaline, also known as Schorl, is the most common variety of tourmaline, accounting for about 95% of all natural tourmaline. It is known for its strong electrical properties; when heated or subjected to pressure, it generates an electric charge (pyroelectricity and piezoelectricity). The name 'tourmaline' comes from the Sinhalese word 'turmali,' meaning 'mixed colored stones,' reflecting the wide range of colors tourmaline can exhibit, though this specimen is uniformly black.

To identify black tourmaline in the field: Look for its opaque black color, vitreous luster, and characteristic prismatic crystal shape with vertical striations (though tumbled specimens like this one won't show the crystal habit). It is harder than steel, so it will scratch glass. Common locations include Brazil, Pakistan, Afghanistan, Africa (e.g., Namibia, Tanzania), and the United States (e.g., Maine, California). Tips for collectors: Black tourmaline is widely available and relatively affordable, making it a good starting point for mineral collectors. Tumbled stones are popular for jewelry and energy work. Larger, well-formed crystals are highly prized.