51 
The smaller crystals are transparent, larger ones are scarcely 
translucent. The fracture is uneven to conchoidal, the 
hardness = 3*5—4’0, the specific gravity = 5’7—6’0. 
Cuprite is, in its pure state, protoxide of copper (Gu), 
composed of 88*78 of copper and 11*22 of oxygen, and is 
therefore a very valuable copper ore. It is reducible on 
the charcoal, and colours the flame green. In acids it is 
readily soluble. 
The ziegelerz, or tile-ore , is a brown-red cuprite, con¬ 
taining oxide of iron, frequently mixed with copper pyrites, 
which occurs in dense masses, especially with malachite, as 
in Fig. 11, in the Scharzwald, at the Herrensegen and St. 
Michael mines, in Nassau and Thuringia, in Chili, and at 
several Cornish mines, and is also smelted to copper. 
Fig. 4—7.—Azurite, Chessylite, Blue Carbonate of 
Copper, Blue Copper. 
Crystallises in oblique rhombic prisms of 98° 15', which 
often occur in elegant groups, sometimes covered with 
small needles of malachite, as, for example, at Chessy (Fig. 
4). Low tables are also found with truncation of the ob¬ 
tuse lateral edges and of the obtuse angles (Fig. 5), or with 
truncation of the obtuse basal edges and of the acute 
angles (Fig. 6), and radiating foliated aggregations (Fig. 
7) are also found. The last-mentioned specimen is from 
the veins of the variegated sandstone of Neubulach in the 
Schwarzwald (Black Forest). It is, moreover, found excep¬ 
tionally, earthy and shrub-like, of a dark blue, as in Hun¬ 
gary and at the Urals. The colour is generally of a deep 
azure blue, often very sparkling; sometimes it is lighter. 
The crystals are of vitreous lustre, translucent, sometimes 
dull, of conchoidal or even fracture, brittle, of from 3*5—4*0 
hardness, and 3*83—3*90 specific gravity. The composi¬ 
tion is 2 eq. of carbonate of copper, and 1 eq. of hydrous 
oxide of copper (2 Cu C + Cu H). Before the blow-pipe it 
melts, and yields a grain of copper on the charcoal. In the 
closed tube it gives out water, and remains as black oxide 
of copper. 
The distribution of this ore is not wide; the fin est, 
crystals are found at Chessy; and in Hungary, where it 
occurs pure, when reduced to a fine powder, it is sold as 
a blue paint of a bright tint ; but is of little value, owing 
to its liability to become green ; it is sometimes also smelted 
with other copper ores. 
Fig. 8 —12.— Malachite, Green Carbonate of 
Copper. 
Crystallises likewise in oblique rhombic prisms, of 103° 
42b which sometimes occur in small bundles of crystals, as 
in Fig. 8, and are generally acicular; truncations of the 
obtuse lateral edges and twin composition, as in Fig. 9, 
are also found; radiated fibrous masses of the finest eme¬ 
rald-green as, for instance, in Siberia (Fig. 10), or dark- 
green bunches (Fig. 11), as at the Herrensegen in the 
Schwarzwald, are more frequent. These are all encrusted 
on a compact red ore. The compact malachite occurs 
tuberose, botryoidal, and reniform, of a more decided blue- 
green colour, in Siberia (Fig. 12). Earthy malachite is 
found with the other varieties, and also in Hungary, and 
in the Schwarzwald. 
The colour varies from dark, or blackish-green, and 
emerald-green to blue and whitish-green. The lustre is 
between vitreous and silky; the fracture is uneven; the 
hardness 3*5—4*0, the specific gravity 3*67—40. The 
crystals or fine needles only are transparent. The com¬ 
position is subcarbonate of copper and \ eq. water; the 
chemical relations are the same as those of azurite. It is 
also in the same way used for copper. The larger, pure 
pieces of the fibrous and compact malachite of Siberia are, 
moreover, used for making small objects of ornament and 
art. The mines of Count Demidoff at Nischni-Tagilsk 
yield extraordinarily fine specimens, which sometimes 
measure several cubic feet, so that whole tops of tables 
and vases have been made from them. Australia now 
furnishes us with specimens of malachite which are scarcely 
inferior in appearance to the finest Siberian varieties. 
Fig. 13—15.— Phosphate of Copper. 
There are two phosphates of copper, one prismatic, 
the other octahedral; the former (Fig. 13) is known as 
phospho-calcite , pseudo-malachite , or Lunnite., the latter as 
lihethenite (Figs. 14 and 15). 
Phospho-calcite crystallises in oblique rhombic prisms ; 
it occurs, however, more frequently in acicular and drusi- 
form crystals; it has the appearance of malachite. It is a 
phosphate of copper with 1 eq. of water, emerald green, 
translucent, of 4*5—5*0 hardness, and 4*2 specific gravity, 
and is soluble in acids without effervescence. It is found 
at Rheinbreitenbach and in Peru, and compact with 
the appearance of compact malachite at Libethen in 
Hungary, the so-called prasim. Only one specimen has 
yet been found in Britain, “ it is from Cornwall, and is 
now in Mr. Greg’s collection.” (Greg and Lettsom, p. 
323.) Libethenite crystallises in rectangular octahe¬ 
drons (Fig. 14), and in combination with the rhombic 
prism and truncation with two vertical edges (Fig. 15), 
of dark, olive-green colour, generally imbedded in quartz 
at Libethen in Hungary. The crystals are of vitreous 
lustre, translucent, brittle, of 4*0 hardness and 3*6—3*8 
specific gravity, and dissolves without effervescence in 
nitric acid. The composition is phosphate of copper, with 
2 eq. of water. Occurs also at Rheinbreitenbach and in 
Cornwall. 
Figs. 16 and 17.— Emerald Copper, Dioptase, 
Achirite. 
One of the finest copper ores, with the colour and ap¬ 
pearance of the finest emeralds. The primary form is a 
rhombic hexahedron, of which however the basal edges are 
truncated, as in Fig. 17. The primary form also occurs 
with extension of two pairs of planes, so that the crystals 
are oblique rhombic prisms, like Fig. 16; they are gene¬ 
rally imbedded in quartz ; brittle, of vitreous lustre, trans¬ 
parent, hardness 5*0, specific gravity 3*27, composition 
two-thirds of silicate of copper, with 3 eq. of water. 
Soluble in nitric acid, separating a jelly of silica, and be¬ 
fore the blow-pipe it gives the reactions of oxide of copper 
