DANBURITE, a rare mineral species consisting of calcium and boron orthosilicate, crystallizing in the ortho rhombic system and discovered in 1839 at Danbury, Conn., whence its name, and where it occurs embedded in dolomite. The crystals are transparent to translucent, and colourless to pale yellow ; they are prismatic in habit, and closely resemble topaz in form and interfacial angles. There is an imperfect cleavage paral lel to the basal plane; hardness 7; specific gravity 3.o. Splendid crystals have been found in Japan.