ARSENIC. 
439 
In Massachusetts, this mineral is found at Shutesbury. It also occurs in crystals and large 
plates at Haddam and the adjoining towns in Connecticut. A large vein has been also found 
at Westmoreland in Vermont. 
ORDER IX. ARSENIC. 
1. Orpiment. 
ORPIMENT. 
(From the Latin auripigmentum, paint of gold; in allusion to its colour, and because it was formerly 
thought to contain that metal.) 
Arsenic Sulfure Jaune. Ilamj. — Orpiment. Cleaveland, Shepard and Beudant .— Sulphuret of Arsenic. Phil- 
lips. — Sesquisulphide of Arsenic. Thomson. — Prismatoidal Sulphur. Jameson. — Prismatoidischcr Schvvefel. 
Mohs. 
Description. Colour bright lemon-yellow. Streak similar, 
but paler. It occurs regularly crystallized; also massive, dis¬ 
seminated, reniform, stalactitic, botryoidal, in crusts and efflores¬ 
cences. The crystals are minute, and the primary form is a right 
rhombic prism. Fig. 532. M on M' 100° (Phillips). Lustre be¬ 
tween adamantine and semi-metallic. Semi-transparent or trans¬ 
lucent on the edges. Sectile. Flexible, but not elastic. Hardness 
from 1.5 to 2.0. Specific gravity from 3.40 to 3.60. Before 
the blowpipe, on charcoal, it fuses readily, and volatilizes with a strong arsenical smoke. 
When subjected to heat in a tube, it melts and deposits yellow crystals in the upper part. 
It is soluble in caustic potash, and muriatic acid precipitates from this solution lemon- 
yellow flocks. 
Composition. Arsenic 61.86, sulphur 38.14 (Laugier). Formula AsS 3 . 
Geological Situation. It occurs in metalliferous veins in primitive rocks, with galena, 
blende, and other ores of arsenic. At Tajowa in lower Hungary, it is found in blue clay. 
Uses. When it occurs in sufficient abundance, it is used with the other ores for obtaining 
the metal. The same compound, artificially prepared, was formerly much employed as a 
paint, under the name of Kings’ yellow. 
Fig. 532. 
