62 
the direction of the planes of a right rhombic prism. 
The crystals are seldom simple, but mostly aggregated as 
twins, triplets, or even in combinations of six crystals, 
like Figs. 4 and 8. These are either hexagonal double 
pyramids, like Fig. 5, or hexagonal prisms with trunca¬ 
tion of the basal edges, like Fig. 6, the latter not unfre- 
quently assuming a tubular appearance, through the 
extension of the two lateral and terminal planes, or they 
are grouped in a stellate form as in Fig. 8. The crystals 
are white, passing into yellowish and grey, generally of 
strong adamantine lustre, but sometimes, especially if they 
are acicular, the lustre is resinous or pearly; sometimes 
they are blackened by sulphuret of lead and of metallic 
lustre, and they are then known as black lead ore. There 
are also lead-spars coloured green and blue by malachite 
and lazulite, which are for this reason called green and 
blue lead spars; reddish and brown-coloured varieties also 
occur. The sulphato-carbonate of lead , or lanarkite , like 
the sulphate of lead, gives, with soda in the reducing flame, 
the distinct reaction of sulphur. The fracture is uneven 
to conchoidal, of strong resinous lustre, the hardness = 
3-0—3*5, and the specific gravity = 6*34—6*48. The 
chemical constituents are simple carbonate of lead, Pb C, 
composed of 82 of oxide of lead, and 16 of carbonic acid. 
Before the blow-pipe it decrepitates and is reduced, 
whereby the charcoal is coated with yellow oxide of lead. 
In nitric acid it is soluble with effervescence. 
It is found in all situations where lead-glance occurs, 
frequently as of more recent production, especially fine at 
Mies and Przibram in Bohemia, Badenweiler in the 
Schwarzwald, Tarnowitz in Silesia, in England and Scot¬ 
land, North America, etc., and is usually smelted with 
the other lead ores. 
Fig. 9 —11.— Anglesite, Lead Vitriol, Sulphate of 
Lead. 
This likewise crystallises in rhombic octahedrons, but 
more frequently presents simple and regular forms, like 
the white lead-ore ; the simple rhombic prisms are princi¬ 
pally found with truncations of the angles as in Fig. 9, or 
rhombic tables with truncation of the obtuse angles, as in 
Fig. 10, or with truncation of the angles and edges, as in 
Fig. 11. The crystals are distinguished by their high 
degree of lustre, between adamantine and vitreous, and 
are frequently set in groups as ornaments. They are colour¬ 
less, passing into yellow, rarely bluish or greenish, trans¬ 
parent to translucent, of small conchoidal fracture; friable, 
of 3-0 hardness, and 6'2—6-3 specific gravity. 
The elements are simple sulphate of lead, Pb S, 
composed of 73*56 oxide of lead, and 26*44 sulphuric acid, 
with occasional traces of water. It melts before the 
blow-pipe to a clear pearl, which becomes milky on 
cooling, and yields in the inner flame a grain of lead. 
In hot nitric acid it is soluble in small quantity, and 
without effervescence. When held in the inner flame, on 
charcoal with soda, the charcoal becomes coated with flour 
of sulphur, and a grain of lead is separated. 
It is found especially at Iglesias in Sardinia, whence 
the crystals, Figs. 9 and 10 were obtained, at Anglesea in 
Wales, at Hausbaden near Badenweiler, and Herrensegen 
in the Schwarzwald, also at the Harz, Westerwald, in 
Hungary, and Siberia. 
The linarite , or cupreous sulphate of lead , is a sulphate 
of lead containing the hydrous oxide of copper of an azure- 
blue colour, crystallising in oblique rhombic prisms, which 
occurs at Leadhills in Lanarkshire, at the Herrensegen, 
and at Linares in Spain. The caledonite is a sulphate of 
lead containing carbonate of lead and carbonate of copper, 
of a bluish-green colour, which crystallises in right rhombic 
prisms, and also occurs at Leadhills. 
Fig. 12—15. —Variegated Lead Ore, Pyromorphite, 
Mimetite. 
Crystallises in hexagonal double pyramids and prisms. 
The former are in general truncated at the vertex, as in 
Fig. 14, the latter are sometimes simple and extended, 
like Fig. 13, sometimes flat and truncated at the basal 
edges, like Fig. 15; the prisms are also frequently barrel¬ 
shaped and striated longitudinally, as in Fig. 12. Besides 
these, acicular, botryoidal, stalactitic, and reniform aggre¬ 
gations are found. The colour varies from pure, to dirty 
green, yellow, and reddish-brown; the former is known 
as green-lead ore, and the latter as brown-lead ore. The 
lustre is in general slight, varying between vitreous and 
fatty, the fracture is uneven. Semi-transparent to trans¬ 
lucent, the hardness = 3*5—4*0, specific gravity = 7*0 
—7*2. 
The chemical constituents are different in almost every 
locality, so much so that many, especially of the green 
ores, consist only of phosphate of lead, others, such as 
many of the yellow and brown coloured ores, of arse- 
niate of lead, while others are composed of both, but in 
different proportions, and again others contain some chloride 
and fluoride of lead, or phosphate and arseniate of lime, 
and fluoride of calcium, or even some vanadate of lead ; 
the oxides of chrome and silver are obtained in small 
amount in many varieties. In the same manner, the be¬ 
haviour before the blow-pipe varies according to their con¬ 
stitution ; in general they all melt readily in the inner 
flame to a globule, which gives off more or less arsenical 
fumes, and after cooling, becomes milky and covered with 
planes of crystals. This pearl is observed as a flat hexa¬ 
gonal prism with curved faces, or as an hexagonal lens. 
By continued blowing the test becomes covered with a 
yellow coating of lead ashes. Phosphates only are present, 
and thus the test gives off no fumes, but the flame is 
coloured slightly greenish. If compounds of chlorine be 
present, and some protoxide of copper added thereto, the 
flame takes a fine blue colour. In hot nitric acid it dis¬ 
solves almost perfectly without effervescence. 
The following varieties are distinguished:— 
1. Pyromorphite , or green lead ore , which is generally 
brownish-green and crystallises in hexagonal prisms, but 
sometimes appears of a light or yellowish green colour. 
It consists, in great part, of phosphate of lead, with from 
2 to 12 per cent of chloride of lead, and is found princi¬ 
pally at the Herrensegen, at Hofsgrund and Badenweiler 
in the Schwarzwald, at Ems in Nassau, Claustlial in the 
Harz, in England, Scotland, and Bohemia. 
2. Arseniate of lead , or mimetite. Principally com¬ 
posed of arseniate of lead with some chloride of lead and 
