indicolita

Indicolita, also known as indicolite, is the blue variety of tourmaline, a complex borosilicate mineral in the tourmaline group. The blue color is typically caused by iron (Fe2+) substituting into the crystal structure, sometimes producing a blue-to-blue-green appearance. Indicolite is a member of the elbaite subgroup, and blue tourmalines gathered under this name are often referred to collectively as indicolite in gemstone contexts.

In terms of composition and properties, tourmalines belong to the XY3Z6(T6O18)(BO3)3 family with extensive chemical substitutions that produce a range of colors. Indicolite crystals are usually transparent to translucent, with a vitreous luster and a Mohs hardness of about 7 to 7.5. They exhibit strong pleochroism, appearing blue along one axis and greenish-blue along another. Crystals are commonly prismatic with well-formed pyramidal terminations and occur in a variety of sizes.

Occurrence and formation sites include granitic pegmatites and some metamorphic rocks. Major sources of indicolite have included Brazil, Afghanistan, Madagascar, Nigeria, Mozambique, and Tanzania, with additional finds in other mining regions, including parts of the United States. Indicolite is often associated with quartz, feldspar, micas, and sometimes spodumene, reflecting its pegmatitic and metamorphic origins.

Uses and nomenclature: indicolite is valued as a blue gemstone, typically cut to highlight color and clarity. Color saturation, size, and transparency influence value, while distinctions from other blue tourmalines—such as paraiba, which derives its color from copper—center on hue and intensity. In practice, indicolite refers to the blue variety of tourmaline in scientific contexts, while indicolita is the term used in some languages.