29 
OKES OF LEAD, 
It forms a constituent part of many of the lodes of copper and tin 
ill Cornwall and Devon, and is generally termed by the miners arsenical 
mundic. The well known poisonous substance white arsenic {arsenious 
acid) is produced from this ore at our western mines to the amount of 
from 1,400 to 1,600 tons per annum 
698 & 699. MisriCKEL, mas¬ 
sive. 
Dole oath, Cormvall. 
Presented by Captain Petherick. 
700. Mispickel, crystalline, ir¬ 
regularly columnar. 
Huel Maudlin, near Lostwithiel. 
701. Mispickel, massive. 
Calstock United Mines, near Cal- 
lington, Cornwall. 
702 & 703. Mispickel, with 
Copper Pyrites, crystallized and 
massive. 
Virtuous Lady Mine, Tavistoch, 
Devonshire. 
704. Mispickel, massive, in 
Quartz. 
Faithleg, County Waterfoixl. 
705. Mispickel, massive. 
Calstock United Mines, near Cal- 
lington, Cormvall. 
Okes of Lead. 
The metal Lead is extracted almost exclusively from the ore called 
Galena, (Sulphide of Lead,) a mineral of bluish-gray colour, crystalli¬ 
zing in cubes, octohedrons, and other forms derived from these. It is 
composed, when in the condition of greatest purity, of 
Lead 86'58 
Sulphur 13*42 
Galena almost always contains a small proportion of silver, varying 
from 2 ozs. per ton of lead in our Midland limestone districts, and 
14 ozs. in the Northern and Welsh limestones, to as much as 80 ozs. 
per ton of lead in the clay slate regions of the Western counties, and to 
some occasionally higher per-centages in isolated cases in Cornwall, 
North Wales, and Ireland. 
In the year 1856 there were produced, from 330 mines, in the 
United Kingdom 101,997 tons of lead ore, equivalent to 73,129 tons 
of metallic lead, from which were separated 614,188 ozs. of silver. 
In 1863 the quantities raised were somewhat smaller, being 91,283 tons 
of lead ore, which produced 68,221 tons of lead, and 634,004 ozs. of silver. 
The ores of lead occur in Cornwall and Devon in the clay slate or 
“ killas ” in regular veins or lodes, most of which course North and 
South ; although a few take an opposite direction. They are largely 
Avorked also, in lodes coursing chiefly East and West, in the carbonife¬ 
rous limestone of Derbyshire, Flintshire, Yorkshire, Cumberland, North¬ 
umberland, and Durham, and in the millstone-grit of Yorkshire ; in 
East and West lodes in the clay slates of Shropshire and Wales ; in 
lodes with various directions in the clay slate of the Isle of Man ; 
in lodes intersecting granite in Scotland and Ireland ; in pipe-veins, 
flats, and other irregular deposits in the limestone of Derbyshire, York¬ 
shire, and Ireland, and in small quantities in the coal-measures of seve¬ 
ral localities. The minerals associated Avith Galena are commonly iron- 
pyrites, zinc-blende, quartz, calcareous spar, barytes, andfluor spar, some 
of them being much more abundant than others in particular districts. 
Veins or other repositories of galena frequently yield near the surface 
several of the minerals afterwards enumerated, Avhich are occasionally 
also employed for the production of lead. 
The specimens of Galena are arranged geographically, beginning 
Avith the South-western part of England. 
