Fig. 505. 



COPPER. 423 



COPPER PYRITES. 



Cuivrc Pyritcux. i7«u(/. — Pyritous Copper. Clcariiaml , — Copper Pyrites. Pkilltps and Th/imsim. Yellow 



Copper Pyrites. Sifi'ard. — Pyramidal Copper Pyrites. Jameson. — Pyramidaler Kupfer-Kies. M.ihs. Clialko- 



pyrite. Bcudant. 



De.scription. Colour brass-yellow, sometimes iridescent. Streak greenish black and feebly 

 shining. It occurs regularly crystallized, massive and disseminated. The primary form is 

 the octahedron with a square base. Fig. 505. P on P' 125=" 30' ; P 

 on P and P' on P' 102° 30'. But the usual shape of the crystal is a 

 tetrahedron, with the angles replaced by small triangular planes. Frac- 

 ture uneven or conchoidal. Lustre metallic. Brittle. Rather scctile. 

 Hardness from 3.5 to 4.0. Specificgravity from4.15 to 4.30. Fusible 

 before the blowpipe into globules, which become magnetic if the blast 

 is continued for some time ; with borax, it yields a globule of copper. 

 It is soluble in nitric acid, leaving sulphur. The solution assumes a 

 blue colour upon the addition of a sufficient quantity of ammonia, and 

 gives an abundant precipitate of the red o.xide of iron. 



Composition. Specimen from Furstenherg — Copper 33.12, iron 30.00, sulphur 3(5.52, 

 silica 0.39 {Rose). 



Specimen from Allevar — Copper 31.10, iron 31.50, sulphur 3fi.30 (BcrtJuer). Ac- 

 cording to Beudant, the formula is Cu,S-|-FeS. 



Geological Situation. This mineral is found in veins, in beds and large masses, in pri- 

 mitive, transition and secondary rocks. In this State, it is almost always associated with 

 galena, and is found in the primary rocks of the northern counties, in the sandstone of the 

 Shawangunk mountains, and in the limestones of the west. 



LOCALITIES. 



Columbia County. Copper pyrites, of a fine brass-yellow colour, is usually associated in 

 greater or less quantities with the galena and zinc blende found in various parts of this county. 

 The best specimens that I have seen are from the Ancram lead mine, where the copper pyrites 

 occurs in masses of considerable size, and has the bcauliful blue tarnish which may be nn's- 

 taken for the blue carbonate of copper. It is here as elsewhere intermixed with galena and 

 zinc blende, and is often associated with quartz and sulphate of barytes. 



Dutchess County. As the veins of galena which occur in Columbia usually extend into 

 this county, it may be inferred that the copper pyrites is also found here. There are hence 

 a number of localities, and among these may be mentioned that on the farm of Judge Bockec, 

 where it is associated with the blue and green carbonate of copper, as well as with galena and 

 zinc blende. The same mineral is also found in small (luaiitities. with similar associates, in 

 the town of Anienia. 



