Sulphuret of Bismuth

Sulphuret of Bismuth is an old well-known, but not abundant mineral; its form and brittleness distinguish it from native Bismuth, and its lighter steel grey colour, inclining to yellowish, from Sulphuret of Antimony. Its easy fusibility is also a useful character; a fibre of it melts as soon as it comes in contact with the flame of a candle. The form of its nucleus, according to Haüy, is a slightly rhomboidal prism, divisible in the direction of its short diagonal; this section produces a brighter face than those of the prism, and is more readily perceived. Bournon has determined the primitive form to be a rhomboidal prism of 60° and 120°: the crystals that afforded the Count the means of ascertaining this point, were very small and thin plates, but well defined and brilliant, and shewed the fracture parallel to their edges, and also in the direction of their diagonals: such crystals are extremely scarce.

The spec. grav. according to Brisson, is 6.4672, or Kirwan 6.131.

Saye obtained from it 60 per cent, of Bismuth and 40 of Sulphur.

It has been found in Bohemia, Saxony, Sweden, and according to Aikin, in Herland mine, Cornwall.