4 PHYSIOGRAPHY. CLASS II. 



Some yield arsenic, others antimony, when roasted, and the 

 residue melts in different ways. After roasting, they yield 

 a globule of copper. 



3. The tetrahedral Copper-glance partakes in the modes 

 of occurrence of the pyramidal Copper-pyrites, and is found 

 in beds and veins ; but it occurs seldom or not at all in the 

 repositories of Tin-ore. It is accompanied by the same 

 minerals as pyramidal Copper-pyrites, frequently also by 

 prismatic Hal-baryte. 



4. Varieties considered as Fahlerz are found in veins near 

 Freiberg in Saxony, and in beds in Anhalt, in the county 

 of Gomor in Hungary, in Stiria, &c. ; varieties called 

 Schwarzerz are met with in veins at Schwatz and other 

 places in Tyrol, at Kapnik in Transylvania, at Cremnitz 

 in Hungary, also at Clausthal and Andreasberg in the 

 Hartz. Tetrahedral Copper-glance occurs besides in the 

 neighbourhood of Dillenburg; in Mansfeld; in small quan- 

 tities at Airthrie and other places in Scotland; in Cornwall, 

 and in America. 



%. PRISMATOIDAL COPPER-GLANCE. 



Prismatic Antimony-Glance. JAM. Syst. Vol. III. p. 

 407. Prismatoidal Copper-Glance. Man. p. 277- 



Fundamental form. Scalene four-sided pyramid of 

 unknown dimensions. Vol. I. Fig. 7. 



Simple forms. P + QD (M) ; Pr (P) ; f r -f oo (h). 



Char, of Comb. Prismatic. Combination. 1. Pr. 

 P -f- co. Pr -f- oo. Sim. Fig. 9. 



Cleavage, ?r -j- QD rather perfect, though inter- 

 rupted. Fracture imperfect conchoidal. Surface 

 rough. 



Lustre metallic. Colour blackish lead-grey. Streak 

 unchanged. 



Brittle. Hardness = 3-0. Sp. Gr. = 5-735. 



