69 
in regular octahedrons, and in right rhombic prisms. 
The octahedral oxide of antimony or senarmontite , crystal¬ 
lises in regular octahedrons, as in Fig. 10, of remarkable 
adamantine lustre, 2-5 hardness, and 5*3 specific gravity, 
and consists of 2 equivalents of antimony = 84.32, and 3 
equivalents of oxygen = 15-68 ; it melts before the blow¬ 
pipe, is reduced and volatilises; with borax it gives a 
greyish-white pearl. 
The prismatic white antimony, also known as anti¬ 
mony-bloom and valentinite, crystallizes in right rhombic 
white plates of pearly lustre, which are translucent, and 
possess a hardness of 2’5—3-0, a specific gravity 5-5—5'6, 
and are otherwise like senarmontite. Senarmontite has 
as yet only been found in the province of Constantine in 
Algiers, and at Perneck in Hungary; it occurs in great 
masses, however, in Constantine; Valentinite, on the 
other hand, is only found very sparingly at Przibram, 
Braunsdorf, etc. 
The antimony ochre forms a yellowish, earthy encrus¬ 
tation, which is principally found as a product of decom¬ 
position, in the form of a yellowish efflorescence on anti- 
monite, and is a mixture of antimonious acid, oxide of 
antimony and water; it has not been applied to any 
purpose. 
Fig. 11—20.— Arsenic Ores. 
Arsenic is a friable metal which has been long known, 
and which is allied to the metalloids by its electro-negative 
properties, and not unfrequently occurs native as well as 
in combination with sulphur and oxygen, and also fre¬ 
quently with other metals, such as silver, antimony, copper, 
nickel, cobalt, etc. Most of its compounds, especially 
those with oxygen, are very poisonous, and as it is easily 
oxidised, all its compounds are in general hurtful to the 
animal frame. All ores of arsenic before the blow-pipe 
give, at least in the inner flame, a strong, repulsive odour 
of garlic or phosphorus, and a white fume, which is only 
deposited on charcoal in small quantity, and is easily 
volatilised. When heated in a tube they yield partly 
metallic arsenic, partly sulphuret of arsenic, and partly 
sublimed arsenious acid. 
Fig. 11.— Native Arsenic. 
Crystallises in rhombohedrons like antimony; it is 
found, however, more frequently compact or amorphous, 
of a curved scaly structure, and of finely granular to 
smooth fracture. The colour is tin-white to iron-grey, 
the metallic lustre slight, but in a fresh fracture easily re¬ 
cognised, as seen in Fig. 11; it also tarnishes readily with 
a grey efflorescence, which in the streak, however, exhibits 
metallic lustre. The hardness = 3A, the specific gravity 
= 5-7—5"9. Like all metalloids and electro-negative 
metals it becomes electro-negative by rubbing, volatilises 
before the blow-pipe with evolution of a peculiar odour, 
and sublimes in the retort. It is dissolved by nitric acid, 
and changed into arsenic acid. It is found at Andreas- 
berg, Freiberg, Schneeberg, and Joachimsthal, in Hesse, 
Styria, France, in Cornwall, etc. The specimen figured 
(Fig. 11) presents the curved scaly aggregation, and is 
from Andreasberg. 
Arsenic is used in casting shot, for the preparation of 
arsenious acid or white arsenic, and of red and yellow 
arsenic. 
Fig 12—14.— Orpiment, Yellow Sulphuret 
of Arsenic. 
Crystallises in right rhombic prisms, which, however, 
mostly occur with truncations of the obtuse basal angles 
and acute lateral edges, as in Figs. 13 and 14, or in 
crystalline-foliated masses, with longitudinal striation and 
remarkable pearly lustre; also efflorescent and disseminated. 
The colour is citrine to orange-yellow, the streak light- 
yellow, the hardness 1*5—2‘0, the specific gravity 
3-48—3-50. 
/// 
The composition is sesqui-sulphuret of arsenic As, 
consisting of 2 equivalents of arsenic (60*90), and 3 equi¬ 
valents of sulphur (39*10). Sublimes in the retort, and 
is completely consumed on charcoal with a white flame, 
and giving off fumes of sulphur and arsenic. It is soluble 
in nitric acid and caustic ammonia. It occurs principally 
at Kapnik and Moldavia, in Hungary, Fig. 14, and as a 
volcanic product in the Solfatara near Naples, and in other 
localities, and when finely powdered it is used as a pig¬ 
ment under the name of golden paint, and in dyeing in 
the preparation of the cold vats. Most of the orpiment of 
commerce, however, is produced artificially by heating 
ores containing arsenic; it contains also, for the most part, 
some arsenious acid, and has therefore a poisonous in¬ 
fluence on the animal organism. The same thing is true 
as regards realgar. 
Figs. 15 and 16.— Realgar, Red Arsenic. 
Crystallises in oblique rhombic prisms, which, how- 
ever, are for the most part truncated at the lateral edges, 
as in Fig. 16, or also at the basal edges, as in Fig. 15, and 
present a foliated structure corresponding to the primary 
form. It also occurs in capillary, disseminated, compact, 
and earthy forms. 
The colour is light aurora-red passing into orange- 
yellow, the streak is orange-yellow. The crystals are 
readily decomposed by the admission of light, especially at 
the angles and edges ; the vitreous lustre and transparency 
are also lost at the same time, and they become tarnished 
by an orange-yellow layer. The hardness is = 1‘5—2-0, 
the specific gravity 3 - 55—3-60. It is simple sulphuret of 
r 
arsenic As, composed of 70-03 of arsenic and 29’97 of 
sulphur. It behaves before the blow-pipe, and with nitric 
acid, like orpiment. It also occurs in the same localities, 
and is applied to similar purposes. 
Fig. 17.— Mispiokel, Arsenical Pyrites. 
Crystallises in right rhombic prisms, which sometimes 
occur single and sometimes as twins, frequently with 
truncation of the obtuse angles, as in Fig. 17; compact, 
granular, and foliated masses are also found. The colour 
is silver-white, sometimes passing into iron-grey, the lustre 
