Bicolor Tourmaline crystal with blue and greenish tourmaline with white inclusions from Brazil.

21mm long

3.0g

Tourmaline is a complex family of aluminum borosilicate minerals mixed with iron, magnesium, or other metals that, depending on the proportions of its components, may form as red, pink, yellow, brown, black, green, blue or violet. Its prismatic, vertically striated crystals may be long and slender, or thick and columnar, and are uniquely triangular in cross-section.