63 
fluoride of calcium, and sometimes also with some phos¬ 
phate of lead. It has also been called hedyphane. The 
finest crystals are found at Joachimsthal in Bohemia, at 
Caidbeckfell in Cumberland, and at Badenweiler, where it 
also occurs in botryoidal masses. Generally, it is similar 
to Fig. 14. 
3. Kampylite , in curved barrel-like crystals, as in Fig. 
12, orange-yellow passing into red and brown; the crystals 
remarkably curved and bent; principally consisting of 
arseniate of lead, with chromate, phosphate, and vanadate 
of lead, some chloride of lead and vanadate of lime. It is 
found at Alston Moor in Cumberland, and at Badenweiler. 
4. Nussierite , botryoidal and crystallised, greenish- 
yellow, of 5*64 specific weight. It is a pyromorphite, which 
contains chloride of lead and phosphate of lime, and occurs 
at N ussier e, department of Rhone, in France. 
Fig. 16.— Wulfenite, Molybdate of Lead. 
Crystallises in square octahedrons or in square tables, 
sometimes with truncation of the basal edges, and is also 
found in crystalline foliated masses, wax or honey-yellow, 
passing into reddish and brown, of resinous lustre, trans¬ 
lucent, of conehoidal fracture, 3'0 hardness, and from 6’69 
—6 - 76 specific gravity. The composition is molybdate of 
lead = Pb Mo, consisting of 59‘3 oxide of lead, and 405 
molybdic acid. It melts on the charcoal with decrepita¬ 
tion, becomes partly absorbed, and leaves a grain of lead; 
with salt of phosphorus it gives a green bead, and is dis¬ 
solved with difficulty in nitric acid. It is found very fine 
at Bleiberg in Carinthia, in small tables at Badenweiler, 
in the Tyrol, Hungary, and North America, and is used for 
making molybdic acid, and the different molybdic salts, 
especially the molybdate of ammonia, which is used for 
the detection of phosphoric and arsenical acids. 
Fig. 17.— Red Lead Ore, Chromate of Lead, 
Crocoisite. 
The primary form is an oblique rhombic prism, which 
generally occurs with truncation of the basal and lateral 
edges, or foliated, as Fig. 17, sometimes also acicular or 
compact. Various shades of hyacinth-red, with orange- 
yellow streak. Of adamantine to vitreous lustre, translu¬ 
cent; of uneven fracture, 2 - 5—34) hardness, and 6 - 0 specific 
gravity. It is simple chromate of lead, Pb Cr, composed 
of 68’38 oxide of lead and 3L52 chromic acid. It melts 
on the charcoal with decrepitation, is partly reduced, gives 
off fumes of lead, and with borax a green glass; with 
nitric acid a yellow solution is formed. It occurs at 
Beresowsk in Siberia, and in Brazil. 
The Melanochroite is sesqui-chromate of lead, of a 
tile-red colour, and crystallises in right rhombic prisms. 
It is found with the last-mentioned ore. So is the Van- 
quelinite , which occurs in dark green or brownish needles, 
and is composed of chromate of lead and chromate of 
copper. 
The pure red lead ore is used when reduced to powder 
as a pigment, and for the manufacture of chromate of 
potash, and chromate of soda, which find many applications, 
partly as reagents, and partly as colours and in colour print¬ 
ing. It is mostly obtained from the cheaper chromic iron 
stones. 
Fig. 18—21.-— Tin Ores. 
Tin is one of the longest-known metals, which, on 
account of its malleability, white colour, and durable lustre, 
has from the earliest times been employed in all kinds of 
household implements. It melts readily, has a hardness of 
2'0, and a specific gravity of 7’29 ; it crystallises in certain 
conditions, either as regular or as square octahedrons, and 
occurs native only exceptionally in small granules in the 
gold-sand of the Urals. The most abundant tin ore is the 
cassiterite, and it is only obtained from tin-pyrites in small 
quantity. 
Cassiterite, Oxide of Tin, Tin Ore. 
Crystallises in square octahedrons, which are, however, 
usually combined with the square prism, as in Fig. 21, 
or present further truncation of the lateral and vertical 
edges, as well as of the basal angles, Fig. 20. Quadratic 
prisms, with truncations of the basal and lateral edges, are 
more frequent, like Fig. 18, or twins, which, like Fig. 19, 
are composed of segments of such crystals. Granular and 
compact masses also occur, and concentrically fibrous 
wedge-shaped pieces, the so-called wood-tin , Fig. 22. 
The colour varies from light-brown to black, the streak is 
somewhat lighter, the lustre being half adamantine and 
half vitreous; the fracture is uneven to conehoidal; the 
hardness is considerable, 6’0—-7 # 0, so that it gives off 
sparks with a steel; the specific gravity is equal to 6 - 96. 
The composition is oxide of tin = Sn, 78‘26 of tin and 
21‘38 of oxygen. It is not easily decomposed, and can 
only be reduced with difficulty on the charcoal, but more 
readily if some soda is added, and yet more so with 
cyanide of potassium. The grain of tin tarnishes the 
charcoal white, the slag being heated with a drop of cobalt 
solution, becomes light green. It is not dissolved by acids. 
The only important tin ore, which occurs principally at 
Ehrenfriedersdorf, Johann-Georgenstadt, and Geyer in 
Saxony, Joachimsthal, Bohemia, at St. Austle in Corn¬ 
wall, in Spain and France, in Malacca and Banca in the 
East Indies, and is generally melted with the addition of 
any flux between layers of coal. The fibrous or wood-tin 
has been found in the alluvial deposits of Cornwall and 
Mexico. 
Tin is used for all kinds of articles of furniture, for the 
foil of looking-glasses, for lining and coating copper and 
iron vessels and sheet-iron, for alloys of different kinds, 
for instance, with copper, as gun and bell-metal, with 
copper and zinc as bronze and pinchbeck, for the manu¬ 
facture of tin ashes and the various salts of tin, etc. 
Tin pyrites is a compound of sulpliuret of tin and sul- 
phuret of copper, which crystallises in cubes, but for the 
most part occurs in crystalline granular masses of a steel- 
grey to a brass-yellow colour, and of small metallic lustre. 
It is almost always mixed with copper or iron pyrites, 
sometimes also with zinc-blende, and yields on an average 
about 26 per cent, of tin. It is of such rare occurrence in 
England, however, as to be of no value as an ore. 
