Sl'UMIIDKS, ARSENIDES, ANTl.Mi >M1 >I.S 



311 



G. =4.1-4.3; Color, brass-yellow, often tarnished ;md iridex-ent ; 

 Streak, mvenish black; Luster, metallic. 



B.B. In K. F. on coal fuses to a magnetic globule and in (). F. 

 yields an odor of sulphur dioxide. Well roasted and reduced with 

 soda, yields malleable copper buttons. Soluble in hot nitric acid. 



General description. Crystals are not uncommon as simple 

 sphenoids or combinations of the sphenoid, base, and prism. The 

 axial ratio being so near unity these sphenoids have the appearance 

 of tetrahedrons ; such simple forms are found in the Joplin region, 



Fio. 401. Chab 



)halerite on Dolomite. Aurora, Missouri. 



Missouri, on dolomite associated with sphalerite and galena. 

 Other sphenoids both obtuse and acute have been described, and the 

 appearance of the crystal will depend upon which is the predominat- 

 ing form ; the tetragonal trapezohedron o> (576) occurs on crystals 

 from French Creek, Pennsylvania. Twins in which the twinning 

 axis is P, both contact and penetrating, occur; other twins are 

 rare. 



Chalcopyrite is present in all copper mines, especially in the zone 

 below oxidation, and is very widely distributed in other mines ; 



