Black Tourmaline

Hardness: 7-7.5 (Mohs scale); Color: Typically opaque black due to high iron content; Luster: Vitreous to resinous; Crystal structure: Hexagonal (trigonal system) with characteristic striated prisms; Cleavage: Indistinct; Specific Gravity: 3.06-3.26.

Black Tourmaline (Schorl) forms in igneous and metamorphic rocks. It commonly crystallizes in granitic intrusions (like pegmatites and granites) and in metamorphic rocks (schists and gneisses) where boron-rich fluids are present. Its formation is associated with hydrothermal processes and late-stage crystallization of magmatic melts. Geological age varies widely depending on the specific deposit, ranging from Precambrian to more recent times.

Black Tourmaline is widely used in jewelry (often as polished beads or cabochons) due to its striking black color and durability. In industry, it has limited use, though some varieties of tourmaline are used for their piezoelectric properties (though schorl is less common for this than other tourmaline species). Historically, it has been used as a protective stone.

Black Tourmaline is the most common variety of tourmaline, accounting for approximately 95% of all tourmaline found. The name 'schorl' comes from a village in Saxony, Germany, where black tourmaline was found in tin mines. It is often believed to have metaphysical properties, such as protection against negative energy and electromagnetic radiation.

In the field, Black Tourmaline is identified by its opaque black color, vitreous luster, and characteristic striated prismatic crystals (though these may not be apparent in tumbled or beaded forms). It can be found embedded in quartz, feldspar, and mica in granites and pegmatites, or as needles and masses in metamorphic rocks. Common locations include Brazil, Africa (e.g., Namibia, Tanzania), Pakistan, and the United States (e.g., Maine, California). Tips for collectors include looking for well-formed crystals in pegmatite pockets or as inclusions in other minerals.