The n = 3 and n = 6 phases were reported as being co-produced together as a mixture for the first time by Henri Moissan and Alfred Stock in 1900 by briefly heating silicon and boron in a clay vessel.
The tetraboride was first reported as being synthesized directly from the elements in 1960 by three independent groups: Carl Cline and Donald Sands; Ervin Colton; and Cyrill Brosset and Bengt Magnusson.
All the silicon borides are black, crystalline materials of similar density: 2.52 and 2.47 g cm−3, respectively, for the n = 3(4) and 6 compounds.
[3] Both SiB4 - x and SiB6 become superficially oxidized when heated in air or oxygen and each is attacked by boiling sulfuric acid and by fluorine, chlorine, and bromine at high temperatures.
The tetraboride was used in the black coating of some of the space shuttle heat shield tiles.