60 
truncated at the lateral edges and basal angles, and may 
be split in the direction of the short diagonal. More 
frequently it occurs in acicular, or in radiated, sometimes 
foliated, more rarely in columnar or compact masses. Iron- 
grey, giving off colours readily with an iron-black streak; 
hardness 2*5—3*0, specific gravity 4*3 to 4*8. Constitu¬ 
tion, hyperoxide of manganese Mn = 1 equivalent of man¬ 
ganese (63*36), and 2 of oxygen (36*64). It is changed in 
the inner flame on charcoal into a red-brown oxide of man¬ 
ganese, and when heated in a retort, besides slight traces 
of water, it always yields a considerable quantity of oxygen, 
so that a piece of live wood held before it soon takes fire ; 
it is much the best oxide for the preparation of chlorine, 
chloride of lime, and chlorate of potash; on the other hand, 
it has no advantage over the other manganese ores in the 
preparation of colours for enamels. It is found of superior 
quality at Ilmenau in Thuringia, at Villingen, at the 
Schwarzwald, also at the Erzgebirge, in Silesia, Bohemia, 
Hungary, England, etc. 
Fig. 18.—Psilomelane, Compact Grey Oxide of 
Manganese. 
Nodular, botryoidal, reniform, compact, sometimes 
fibrous or scaly, of dark-grey or bluish-black colour, small 
metallic lustre, conchoidal fracture, friable, and very hard, 
with brownish-black streak, hardness = 5*0—6*0, so that 
it gives out feeble sparks when struck against the steel. 
Specific gravity 4*0—4*15. The chemical composition is 
manganate of copper, oxide of manganese, with some 
potass, to which silicic acid and water are also usually 
added. Infusible before the blowpipe, in the retort some 
water is given off, otherwise it has the same relations as the 
other ores of manganese. It is found generally with pyro- 
lusite, at the localities given under that head, also with red 
and brown iron-stone, and is frequently smelted along with 
these. 
The l&ptonemerz of Breithaupt is a similar black man¬ 
ganese ore, which consists of oxide of manganese and 
water ; polianite , which sometimes resembles it, is on the 
other hand manganate of copper of 5*5—6*5 hardness ; both 
of them are found at Aue, near Schneeberg. and at Elgers- 
burg in Thuringia. 
Wad or braunsteinschaum is a dark-brown earthy pro¬ 
toxide of manganese, occurring in loose kidneys or round¬ 
ish masses, extremely light and rich in water, which it 
gives off in the retort; it is brown in colour, and exhibits 
a hardness of 0*5—1*0. It occurs with the other ores of 
manganese, especially at Westerwald, and at Naila in 
Bayreuth. 
Compounds of Manganese. 
The protoxide of manganese has much similarity in 
its relations to the protoxide of iron, and forms with the 
acids rose-red coloured salt compounds. 
The red manganese ore or protocarbonate crystallises 
in rhombohedrons similar to calcite and spathose iron, of 
107° O', according to Breithaupt, and therefore has the 
appearance of a rose-red calcite, translucent; hardness 3*5, j 
specific gravity, 3*4—3*59, and is soluble in acids with I 
effervescence. The constituents are simple carbonate of 
manganese, composed of 61*73 of the protoxide of manga¬ 
nese, 38*27 of carbonic acid = Mn C; it generally con¬ 
tains, however, a little lime, magnesia, and protoxide of 
iron, in addition. It is found principally at Kapnik in 
Hungary, and Naygag in Siebenburg, also in Nassau. 
The so-called himbeerspath of Nassau and Schneeberg in 
Saxony is a calcite containing lime and protoxide of iron, 
and the manganocalcite is a manganite containing lime, 
magnesia, and protoxide of iron. 
The Manganese spar , or Rhodonite , is sesqui-silicate 
of the protoxide of manganese, of a rose-red colour, which 
occurs partly in crystalline, foliated masses, partly com¬ 
pact or finely granular, like Fig. 19 ; the former variety 
may be split in the direction of an oblique rhombic 
prism, and is almost translucent, of splintery fracture ; 
hardness = 5*0—6, so that it gives faint sparks on the 
steel; specific gravity 3*5—3*6. It is melted before the 
blow-pipe to a red pearl, which is blackened in the 
external flame, and with phosphorus yields a skeleton of 
silica. It is found at Elbingerode, at the Harz, at Kapnik 
in Hungary, and in Siberia. The granular variety is 
applied to all kinds of small objects of art, and takes a 
beautiful polish. 
Lead Ores. 
Lead is a bluish-grey, very soft, easily fusible metal, of 
11*4 specific gravity, and 1*5 hardness ; of bright metallic 
lustre, but it soon loses this on exposure to the atmosphere, 
and becomes covered with a grey layer of the suboxide. It 
melts at 612° Fahr., and evaporates in iridiscent vapours 
tolerably quickly, in which are carried off other metals 
also, such as antimony, arsenic, and even some silver. 
It moreover exercises a solvent power on many other 
metals, especially on silver and gold, so that these may 
be separated by it from their various ores, especially if 
they are first roasted, an operation which in many 
furnaces is carried on under the name of silvering or 
eliquation. Lead also serves similar purposes in testing 
silver ore in small quantities, when the contained lead of 
liquidation is refined by bone-ashes. Lead crystallises 
under certain conditions in regular octahedrons, and is 
found only very rarely native, in small grains of metallic 
lustre, partly in lead-glance, as for instance at Alston 
Moor in Cumberland, Carthagena in Spain, in a rock 
containing lava in Madeira, and also in small globules in 
a mass of meteoric iron found at Tarapaca in Chili. Most 
of the lead of commerce is obtained from lead-glance, and 
a few other lead ores. 
The softness and malleability of lead implies a wide 
application of it to tubes, plates, drains, mouldings, types, 
etc. One of the principal purposes to which it is applied 
is the lining of the leaden chambers for the manufacture 
of sulphuric acid, the pans for boiling alum, etc. It is 
also used in the manufacture of different surgical and 
chemical instruments in the soldering of iron railings and 
posts; in the preparation of litharge, red lead, sugar of 
lead, white lead, and other preparations; for lead bullets, 
shot, etc.; as well as for various easily flexible metallic 
mixtures, especially as moulds for letters, stereotype 
! plates, etc. The lead of commerce is not, however, 
