My periodic table poster is now available! Danburite. Description from the source: Danburite (Ca B2 (SiO4)2 orth.), Charcas, San Luis Potosi`, Mexico. Prismatic, geminated. 4x2x1,5 cm; 16 g. Source: Simone Citon Contributor: John Gray Acquired: 19 November, 2008 Text Updated: 20 November, 2008 Price: Trade Size: 1.6" Composition: CaB2(SiO4)2