ARSENIC. 



439 



III Massachusetts, this mineral is found at Shulesbury. 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. 



{Fiomlhe Latin auripig7nentum, paint of gold ; in allusion to its colour, and because it was fonncrly 



thought to contain that metal.) 



Arsenic SuJIure Jauno. //«»y. — Orpiment. Cleavdand, S/icpard a.nd Bcuilant. — Su\i>huTet of Aisenic. Phil- 

 lips. — Sesquisulpliide of Arsenic. Thomson. — Prismatoidal Sulphur. Jameson. — Prismatoidischer Schwefel. 

 Mohs. 



^'^" ^^^- Description. Colour bright lemon-yellow. Streak similar, 



but paler. It occurs regularlj' 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 .A.sSj. 



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. 



