PLATE XY. 
Figs. 1—5.—Mercury, Quicksilver. 
1. Amalgam , a compound of 36 of silver and 64 of mercury, the commonest form of crystal, a rhombic dodecahedron 
with truncation of all the edges (twenty-four sided solid), in combination with the planes of the cube, as it usually occurs at 
Moschel-Landsberg. 
2. Native Quicksilver , in small globules on earthy cinnabar, from Stahlberg in the district of Saarbriick. 
3. Crystalline Cinnabar , dark-red and dense, from Szlana in Hungary. 
4. Crystallised Cinnabar , rhombic hexahedron, with double truncation of the vertex, combination of the acute rhombo- 
hedron, with two obtuse rhombohedrons, from Almaden in Spain. 
5. The same , rhombohedral table, formed by truncation of the vertex, from Idria. 
Figs. 6— 20. —Copper Ore, Native Ore, and Sulphuret of Copper. 
6. Native Copper, icosahedron, distinctly in combination with the cube, together with other crystals of the regular 
system, aggregated in an arborescent form, from Lake Superior, Michigan. 
7. The same , octahedral, cubic, and dodecahedral crystals aggregated and distorted by the extension of individual planes, 
imbedded in granular quartz, from Katharinenberg. 
8. The same , aggregated and branched like a tree (dendritic), with a slight coating of oxide of copper, from Cornwall. 
9. Copper Glance , chalcosine or vitreous copper, in secondary hexagonal pyramids, with truncation of the basal edges 
(rhombic prism with truncation of the acute lateral edges and of the basal edges), partly aggregated as twins, and with an 
indigo-blue tarnish, on quartz, from Cornwall. 
10. The same , rhombic prism, the primary form, with truncation of the acute lateral edges, same locality. 
11. Indigo Copper or Covelline , simple sulphuret of copper, pulverescent, on copper pyrites, from Herrensegen, in the wilds 
of Schapbach in the Black Forest. 
12. Variegated Copper , or Erubeseite , compact, with violet and blue play of colours, from King David mine at Schneeberg 
in Saxony. 
13. Erubeseite , subsulphuret of copper with sulphuret of iron, containing 56'76 of copper, crystallised in regular octa¬ 
hedrons, with a drusy arrangement, from Cornwall. 
14. Copper Pyrites , or Chalcopyrite, simple sulphuret of copper combined with sesqui-sulphuret of iron in equal propor¬ 
tions, containing 34-47 of copper, square octahedrons and quadratic tetrahedrons, with occasional twins, on yellowish brown-spar, 
from Cornwall. 
15. The same , square octahedrons, the primary form. 
1 6. The same , regular tetrahedrons with truncation of the angles, the combination with the second tetrahedron, the most 
usual form. 
17. Tetrahedrite or Grey Copper (fold-ore), in regular tetrahedrons, the primary form, drusy and imbedded in chalcopyrite, 
from the Harz. 
18. The same , tetrahedrons with truncation of the angles, from Kapnik in Hungary. 
19. The same , tetrahedron with double truncation of the edges, pyramidal tetrahedron, from the same place. 
20. The. same , tetrahedron with truncation of the edges (cube), and bevelling of the angles (second pyramidal tetrahedron), 
from the same place. 
