50 
found in dense masses, as for example at Schneeberg (Fig. 
12), of uneven fracture, with violet, blue and green tarnish, 
passing into copper-red, and pinchbeck-brown, with greyish 
black streak, opaque, and of feeble metallic lustre ; slightly 
friable, of 3*0 hardness, and 5*0 specific gravity. It is a 
combination of 4 eq. sub-sulphuret of copper, and 1 eq. of 
/ / 
simple sulphuret of iron (Fe Cu 4 ); the dense ores yield 
from 56-—61 per cent, of copper. Before the blow-pipe 
it behaves like copper-glance, by which the oxide of iron 
is separated. It is found in Nassau, Thuringia, Saxony, 
and Silesia, in Sweden and Norway, and in Cornwall, and 
is everywhere smelted with the other copper ores. 
Figs. 11,14,15,16.-— Copper Pyrites or Chalcopyrite. 
The primary form is a square octahedron, like Fig. 15, 
in which, however, the half of the faces are frequently 
increased at the expense of the others, so that the tetra¬ 
hedral form predominates, as in Fig. 16, or several 
such crystals are united as twins, as in Fig. 14. Most 
frequently dense masses occur of a brass-yellow colour, 
and uneven fracture, like Fig. 11; and these are usually 
mixed with dense sulphur pyrites, so that the ores often 
give a very small share of copper. The colour is always 
deeper yellow than in iron pyrites, and sometimes iri¬ 
descent, with play of colour passing into greenish and 
bluish, or gold-yellow; the streak is greenish-yellow, the 
metallic lustre striking, the hardness = 3*5—4*0, conse¬ 
quently it cannot strike fire with steel, and by this pecu¬ 
liarity it may be readily distinguished from sulphur pyrites. 
Copper pyrites consists of equal proportions of simple 
/ 'n 
sulphuret of copper and sesqui-sulphuret of iron Cu Fe, 
and in a pure condition contains 34*47 of copper, 30*4 of 
iron, and 35*05 of sulphur, to which there is occasionally 
added a small amount of silver or gold. When heated on 
the charcoal it leaves a brown-red residue, from which by 
itself only by continuing the blowing, but more readily 
on the addition of some soda, and, more easily still, with 
cyanide of potassium, a granule of copper is obtained. It 
is one of the most valuable of copper ores, which frequently 
occurs in large layers and blocks in the primary, and older 
stratified formations, as for example at Roraas in Norway, 
at the Rammelsberg near Goslar, at Fahlun in Sweden; it 
also occurs frequently in the Herrensegen and St. Michael 
mines in the Schwarzwald, in Nassau, Styria, Tyrol, 
Silesia, England, and France. The finest crystals, as in 
Figs. 14 and 16, are found in Cornwall, and at the Erzge¬ 
birge in Freiberg. In many places quite poor ores, with 
so low as 6 per cent, of copper, are smelted, when mixed 
with richer varieties ; the sulphurous vapours which are 
given off are also sometimes employed in the preparation 
of sulphuric acid. 
Fig. 17—20.— Grey Copper Ore, Tetrahedrite, 
Fahlore. 
Crystallises in regular tetrahedrons, which are some¬ 
times arranged in a druse, like Fig. 17, and presents an 
indistinct foliated structure, corresponding to the primary 
faces; truncation of the angles, as in Fig. 18, or double 
truncation of the edges, the tetrahedron in combination 
with the pyramidal tetrahedron, as Fig. 19 ; also simple 
truncation of the edges (cube), besides triple replacement 
of the angles (second pyramidal tetrahedron), as Fig. 20, 
and also thick masses, are of frequent occurrence. Steel- 
grey, strongly lustrous, occasionally with a variegated 
tarnish, streak black; friable; fracture conchoidal, un¬ 
even, hardness 3*0—4*1, specific gravity 4*79—5*1. 
The grey copper ores form remarkable double combi¬ 
nations of sulphuret of copper, sulphuret of antimony, or 
sulphuret of arsenic, sometimes with sulphuret of silver, 
sometimes with sulphuret of zinc, or with sulphuret of iron 
and sulphuret of mercury; and in the first rank we dis¬ 
tinguish antimony , and arsenic grey copper , as well as grey 
copper, with and without silver, with zinc, mercury, etc. 
The above-mentioned metallic sulphurets sometimes occur 
in combination with one another, and there are varieties 
containing bismuth and lead as well. The arsenic tetra¬ 
hedrite is usually somewhat lighter in colour, and contains 
38*63—42*50 of copper, with a proportion of silver of 
0*50—2*37. The antimony tetrahedrite, also known as 
schwarzerz, and dark fahlore, contains 14*81—25*50 of 
copper, and 13*25—31*29 of silver. The mercury fahlores 
contain 34*57—35*76 of copper, and 15*57—17*27 of 
mercury. Before the blow-pipe all of them give sulphur¬ 
ous vapours, and more or less antimony or arsenical smoke; 
a grain of copper containing silver remains as a residue on 
the charcoal, from which, by means of lead, and repeated 
refining by animal charcoal, the silver may at last be ob¬ 
tained pure. This is more easily effected in the moist 
way, in which the grain of metal is dissolved in pure 
nitric acid, and the dilute solution precipitated by copper. 
The light fahlore is found at Freiberg, Klausthal, at Kap- 
nik, and Schemnitz in Hungary, at Schwatz in the Tyrol; 
the dark variety also occurs at Freiberg, at St. Wenzel in 
the Schwarzwald, and in Hungary. The fahlores are 
usually smelted for copper and silver, that containing 
quicksilver from Schwatz in the Tyrol, Poratsch in Upper 
Hungary, and Moschellande, also yielding quicksilver. 
/ 
PLATE XVI. 
Fig. 1—3.——Cuprtte, Red Oxide of Copper. 
Crystallises in regular octahedrons, which sometimes 
occur in remarkable groups, as, for example, in Siberia 
(Fig. 1) ; truncations of the edges, as in Fig. 2, and rhom- 
bohedrons, as in Fig. 3, are also found; these are, for the 
most part, covered by a coating of earthy malachite, and 
occur principally at Chessy, near Lyons. Very fine cubes 
are found in Cuba; dark red needles and capillary crystals, 
with a fine velvety silky lustre, which are known as clialco- 
trichite , at the Virneberg at Rheinbreitenbach; dense and 
foliated masses also occur principally in Cornwall and 
Siberia. 
The colour varies from cochineal-red and lead-grey to 
crimson-red; the streak is light to darkish-red, the lustre 
inclining sometimes to adamantine, sometimes to metallic. 
