Danburite (CaB₂(SiO₄)₂) is a calcium borosilicate forming gemmy transparent prismatic crystals. Named after Danbury (Connecticut). It bridges the silicate-borate worlds chemically. Charcas (San Luis Potosí, Mexico) and Russia’s Dal’negorsk supply iconic gem material; the Charcas Mine “champagne” colored crystals are particularly prized.
Key Facts
- Mohs hardness 7–7.5.
- Orthorhombic; prismatic crystals with diagnostic flat-topped pyramidal terminations.
- Borosilicate — chemistry intermediate between silicates and borates.
- Colorless, pink, yellow, or champagne varieties.
- Common matrix for gem-grade rubellite tourmaline at Charcas.
Notable Localities
Charcas (San Luis Potosí, Mexico) is the world standard for gem material. Dal’negorsk (Russia) and Madagascar yield additional collector material.
Found at these Localities
- Naica Mine, Chihuahua (纳伊卡矿(奇瓦瓦州))
- Madagascar Pegmatites (Sahatany / Antsirabe) (马达加斯加伟晶岩区)
