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. 



(Prom the Latin auripigmentum, paint of gold; in allusion to its colour, and because it was formerly 



thought to contain that metal.) 



Arsenic Sulfure Jaunc. flijKy. — Orpiment. Cleaveland, Shepard and J5ea(fan«. — Sulphuret of Arsenic. PAti- 

 lips. — Sesquisulphide of Arsenic. Thomson. — Prismatoidal Sulphur. Jamesim. — Prismatoidischer Schwefel. 

 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 (LaMgzer). Formula AsSj. 



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. 



