10 PHYSIOGRAPHY. CJLASS 11. 



but by a curious anomaly also the crystals, in which but 

 indistinct traces of cleavage can be observed. There exist 

 transitions among all these varieties. 



2. According to KLAPROTH, it consists of 



Copper 76-50 78-50. 



Sulphur 22-00 18-50. 



Iron 0-50 2-25. 



Silica 0-00 0-75. 



It is the sulphuret of copper, Cu S, in which the propor- 

 tion of copper and sulphur is, according to BERZELIUS, = 

 7973 : 20-27. In the oxidating flame of the blowpipe it 

 melts and emits with a noise glowing drops. In the re- 

 ducing flame it becomes covered with a coat, and does not 

 melt. If the sulphur has been driven off, a globule of cop- 

 per remains. In heated nitric acid the copper is dissolved, 

 and the solution assumes a green colour, but the sulphur 

 remains undissolved. 



3. If we except the tetrahedral Copper-glance, the pre- 

 sent species is among those belonging to the genus, the one 

 which occurs most frequently in nature, both in beds and 

 veins. It is associated chiefly with other ores of copper, 

 with hexahedral Iron-pyrites, rhombohedral Quartz, &c. 

 It is one of those minerals which, by decomposition, are 

 converted into copper-black. 



4. Large and well defined crystals of this species occur in 

 several mines near Redruth and in other districts, in Corn- 

 wall. In that place, and in the vicinity of Freiberg, the 

 present species occurs in veins. Compound varieties, and in 

 a few rare instances also crystals, have been found in beds in 

 the Bannat of Temeswar, near Catharinenburg in Siberia, in 

 Mansfeld, in Hessia, &c. ; in the two last countries in bi- 

 tuminous shale. The fossil corn-ears, which were referred 

 by LiNiraus to the genus Phalaris^ from Frankenberg in 

 Hessia, consist in part of prismatic Copper-glance, and con- 

 tain often a little native Silver. Prismatic Copper-Glance 

 is found in the district of Siegen, in the mines of Kupfer- 

 berg and Rudelstadt in Silesia, in Sweden, Norway, and 



