COPPER. 423 



COPPER PYRITES. , 



Cuivre Pyriteux. Hauy. — Pyritous Copper. Ckaveland. — Copper Pyrites. PhiUips and TKomso-n. — Yellow 

 Copper Pyrites. Shepard. — Pyramidal Copper Pyrites. Jameson. — Pyramidaler Kupfer-Kies. Mohs. — Chalko- 

 pyrite. BetiAarU. 



Description. 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° SCK ; 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 metalHc. Brittle. Rather sectile. 

 Hardness from 3 . 5 to 4 . 0. Specific gravity from 4 . 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 oxide of iron. 



Composition. Specimen from Furstenberg — Copper 33.12, iron 30.00, sulphur 36.52, 

 silica 0.39 (Rose). 



Specimen from Allevar — Copper 31.10, iron 31.50, sulphur 36.30 (Berthier). Ac- 

 cording to Beudant, the formula is CuaS-l-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 beautiful blue tarnish which may be mis- 

 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 Bockee, 

 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 quantities, with similar associates, in 

 the town of Amenia. 



