54 
and consists essentially of equal proportions of bi-sulphuret 
of cobalt and bi-arseniuret of cobalt = Co S 3 + Co As 3 ; 
bi-sulphuret of iron also frequently enters into the mixture. 
It gives on the charcoal strong arsenical and sulphureous 
vapours. A piece held in the reducing flame exhibits 
magnetic properties if it contains iron, and the borax 
pearl, saturated with it, appears yellow when heated, but 
becomes dark-blue when cold. It is one of the most 
valuable ores, containing, on an average, 33 per cent, of 
cobalt. 
Figs. 10 and 11.—Smaltine, Geey Cobalt. 
Crystallises in cubes as seen in a few crystals to the 
right of Fig. 11 ; more frequently those at the corners 
are truncated, as in Figs. 10 and 11, so that the octa¬ 
hedron is more or less distinct; rhombic dodecahedrons 
also occur. The crystals may be split principally in the 
directions of the planes of the cube, sometimes also in 
that of the planes of the octahedron. Compact masses 
of a tin-white to a steel-grey colour are very frequent; 
they lose their metallic lustre readily in the air, how¬ 
ever, and become tarnished with a reddish grey. When 
fresh, the mineral always presents a strong metallic 
lustre, and a tin-white colour, more or less inclined to a 
yellowish or iron-grey; the planes of the crystals are 
seldom perfectly even, and do not present the brilliant 
lustre of the ores already mentioned. The fracture is 
uneven, the hardness == 5*5, the specific gravity = 
6*2—6*4; friable. It consists of bi-arseniuret of cobalt 
Co As 2 , containing 20*31 of cobalt, frequently rendered 
impure by a distinct trace of arseniuret of iron, and 
sometimes of sulphuret of copper. 
The Iron-smaltine of Schneeberg contains only 9*44 of 
cobalt and 18*48 of iron. 
Before the blow-pipe smaltine gives a strong arsenical 
-smoke, and if it contains sulphur, along with soda it gives 
a slag, which on a wet silver coin leaves a black mark; in 
the retort, when heated, it gives a sublimate of metallic 
arsenic. 
It is the commonest ore of cobalt, and occasionally 
also occurs in very compact masses, as for example at 
Schneeberg, Saalfeld, in Nassau and Hesse, Schladming 
in Styria, Wittich and Wolfach in the Schwarzwald, etc. 
It occurs along with native bismuth, under the name of 
cobalt bismuth ore , at Schneeberg, and with nickel at 
Riechelsdorf in Hesse. 
Earthy cobalt , or black cobalt , is of a bluish-black 
colour, dim, earthy, sometimes botryoidal, or as pseudo- 
morphs of calcite (the kakochlor of Breithaupt), and appears 
to be a product of decomposition of smaltine and other cobalt 
ores, and generally contains oxide of manganese and water. 
The cobalt is sometimes contained in it as the oxide or 
hydrous oxide, and sometimes as the sulphuret and 
arseniuret of cobalt. There are also varieties which con¬ 
tain the oxides of copper and iron; most of them are, 
however, rich in the oxide of manganese, which may be 
easily recognised by the bluish-green colour which the 
assay takes on being held in the point of the flame with 
soda on platinum wire. It is found, for the most part, in 
combination with other cobalt ores, at the Schwarzwald, in 
Hesse, Saxony, and Thuringia. The Kakochlor has until 
the present time only been found in the Spitzleite mines. 
Silver-cobalt, which was formerly found at the mines 
in the Schwarzwald, in the Reinerzau, and at Wittich, is 
a black earthy cobalt with hematite and native silver dis¬ 
seminated throughout it. 
Figs. 12 and 13. —Cobalt-Bloom. 
Crystallises in oblique rectangular prisms, which are 
generally in combination with truncation of the lateral 
and basal edges, as in Fig. 13, more frequently in crystal¬ 
line foliated radiate bundles or crystals, Fig. 12. The 
specimens figured are from Schneeberg; they were for¬ 
merly found, however, at the Schwarzwald. It is found 
in old veins as a product of decomposition of smaltine as 
an earthy crust, or red earthy cobalt, partly mixed with 
pharmacolite. The colour is a brilliant crimson to scarlet, 
the lustre is pearly, it is translucent, flexible in thin laminse, 
the hardness is = 1*5—2*0 and the sp. gr. = 2*9—3*0. It 
is arsenical oxide of copper, with 6 equivalents of water, 
and is similar in composition to the crocidolite or blue 
asbestus, the form of whose crystals it also takes— i.e., 
it is isomorphous with it. It is found principally with 
the other ores of cobalt; it occurs very fine at Riechels- 
dorf in Hesse, and at Schneeberg in Saxony. 
PLATE XVII. Fig. 14—17, PLATES XVIII. and XIX. Fig. 1—10. 
Iron Ores. 
Iron, undoubtedly the most useful of all metals, is at 
the same time very generally distributed; it is found not 
only in all formations, but also in all high mountains, and 
even in level plains. It is not, indeed, everywhere pre¬ 
sent in such considerable quantities as to be readily ob¬ 
tained, yet it is nowhere quite absent, as the colours of 
rocks and soils, and sometimes also the contents of mineral 
waters, prove. Indeed, when black or red-coloured rocks, 
red or dirty-yellow coloured soils occur, or when a spring 
deposits an ochrey-yellow mud, we may be sure that a 
quantity of iron is present; and it so happens that the ashes 
of most vegetables, the solid and fluid parts of animals, but 
especially their blood and flesh, generally contain a consider¬ 
able amount of iron. 
Iron is found native only exceptionally, and then it is 
usually of meteoric origin. In general it is mineralised 
by sulphur or oxygen, or combined as an oxide with silicic 
and other acids; and as it is only the compounds with 
oxygen that are used for obtaining iron, these are usually 
called the iron-ores. On being heated, they all give, when 
held in the reducing flame, a slaggy-looking drop, which is 
attracted by the magnet, and which yields with borax a 
yellow-coloured pearl, which becomes olive to grass-green 
on getting cold. It is soluble by acids to a green fluidity 
