turmaline

Turmaline is a complex borosilicate mineral group composed of aluminum, iron, magnesium, lithium, and other metals. Its chemical composition is distinguished by the presence of aluminum and boron, with varying amounts of other elements determining its color. Turmaline is known for its wide range of colors, including black, brown, green, blue, red, pink, yellow, and colorless. This chromatic diversity is due to the presence of trace amounts of transition metals such as iron, manganese, and chromium.

The mineral crystallizes in a trigonal system and typically forms prismatic, columnar, or acicular crystals. It exhibits a vitreous luster and a Mohs hardness of 7 to 7.5, making it relatively durable. Turmaline is found in a variety of geological environments, including igneous and metamorphic rocks, as well as in alluvial deposits. Major sources include Brazil, Africa, Afghanistan, Pakistan, and the United States.

Historically, turmaline has been used for ornamental purposes, jewelry, and as a gemstone. Its piezoelectric properties, meaning it generates an electric charge when subjected to mechanical stress, have also led to industrial applications, such as in pressure gauges and electronic components. The name "turmaline" is believed to derive from the Singhalese word "turmali," which means "mixed colored stone," reflecting its varied hues.