PHYSIOGRAPHY. 



Orpiment. 



91 



Secondary form. 



Fig. 329. 



M on c 1 20 00 ? } C M' on i 162 38' 



M on/ 140 00 > PHILLIPS. <c one' 83 30 

 Mong 177 54 ) ( c on b 145 50 



Cleavage, parallel with M not very perfect, or only in 

 traces, but parallel with f highly perfect. The faces of 

 cleavage are streaked parallel to the edges of intersection 

 with M. Fracture scarcely observable. Surface, f 

 rough, but even ; all the other faces are streaked parallel 

 to their edges of combination with M, and generally une- 

 ven. 



Lustre pearly metallic upon the perfect faces of cleav- 

 age, the rest resinous. Color, several shades of lemon- 

 yellow. Streak lemon-yellow, generally, a little paler than 

 the color. Semi-transparent . . . translucent on the edges. 

 Sectile. Thin laminae are highly flexible. Hardness 

 = 1 -5 ... 2-0. Sp. gr. 3-4SO, a cleavable variety. 



Compound Varieties. Reniform, botryoidal, and other 

 imitative shapes : composition curved lamellar, faces of 

 composition commonly rough. Massive : composition 

 granular, of various sizes of individuals ; faces of composi- 

 tion uneven, often irregularly streaked. 



1. Before the blow-pips, upon charcoal, it burns with a blue flame, 

 and emits fumes of sulpur and arsenic. It is soluble in the nitric, muri- 

 atic and sulphuric acids. 



