Danburite is a calcium silicate mineral of CaB2(SiO4)2.
It has a Mohs hardness of 7 to 7.5 and a specific gravity The mineral has an orthorhombic It is usually colourless, like quartz, but can also be either pale yellow or yellowish-brown. It typically occurs in contact metamorphic rocks.
The Dana classification of minerals categorizes danburite as a sorosilicate, while the Strunz classification scheme lists it as a tectosilicate its structure can be interpreted as either.
Its crystal symmetry and form are similar to topaz; however, topaz is a calcium fluorine bearing nesosilicate. The clarity, resilience, and strong dispersion of danburite make it valuable as cut stones for jewelry.
It is named for Danbury, Connecticut , United States, where it was first discovered in 1839 by Charles Upham Shephard.