Elbaite

Elbaite

Elbaite is a mineral species belonging to the tourmaline group. It is a complex borosilicate mineral with a wide range of colors, which makes it highly valued as a gemstone. Elbaite is named after the island of Elba, Italy, where it was first discovered.

Chemical Composition

Elbaite has the chemical formula Na(Li,Al)₃Al₆(BO₃)₃Si₆O₁₈(OH)₄. It is a sodium, lithium, and aluminum-rich member of the tourmaline group. The presence of various trace elements can cause a wide range of colors in elbaite, including green, pink, red, blue, and multicolored varieties.

Crystal Structure

Elbaite crystallizes in the trigonal system, typically forming prismatic crystals with a triangular cross-section. The crystals are often vertically striated and can be quite large. The structure of elbaite is characterized by a complex arrangement of silicate tetrahedra, borate groups, and metal cations.

Physical Properties

• Color: Elbaite can be found in a variety of colors, including green, pink, red, blue, and colorless. The color is often zoned, with different colors appearing in the same crystal.
• Luster: Vitreous
• Hardness: 7 to 7.5 on the Mohs scale
• Specific Gravity: Approximately 3.0 to 3.2
• Cleavage: Indistinct
• Fracture: Conchoidal to uneven

Occurrence

Elbaite is commonly found in pegmatites, which are coarse-grained igneous rocks. It is often associated with other minerals such as quartz, feldspar, and lepidolite. Notable localities for elbaite include Brazil, Afghanistan, Madagascar, and the United States.

Uses

Elbaite is primarily used as a gemstone. Its wide range of colors and clarity make it a popular choice for jewelry. The most prized elbaite gemstones are those with vivid colors and high transparency.

Varieties

Elbaite has several well-known varieties based on color:

• Rubellite: Red to pink elbaite
• Indicolite: Blue elbaite
• Verdelite: Green elbaite
• Watermelon Tourmaline: Elbaite with a pink center and green outer zone

Also see

• Tourmaline
• Pegmatite
• Gemstone
• Mineral