gallery.] natural HISTORY. (Minerals.) 45 
massive, in detached crystals and as grains (in the alluvial deposits of 
Guinea, Sumatra, Bengal, Brazil, Leadhills in Scotland, Sec.), also in 
brown iron-stone, in quartz, with needle-ore, &c., in Siberia;—the 
alloyed gold (principally from Transylvania) crystallized in minute 
cubes and octahedrons variously aggregated, in reticular plates, &c. 
Of the native alloys known by the names of electrum , that of Smeof or 
Schlangenberg, in Siberia, is best known: it is said to contain one-third of 
silver; but in general the two metals do not unite in definite proportions. 
In this Table Case begin (continued to Case 12) th^ electro-negative 
metallic substances called metalloids bv Berzelius, and their non- 
oxidized combinations.— Tellurium and tellurets: the scarce native tel - 
lurium, which element (like sulphur and selenium) has the property of mi¬ 
neralizing several metals, combining with them as electro-negative sub¬ 
stance, viz_with bismuth (a compound formerly called molybdena-sil- 
ver) from Bastnaes: to which also belongs the tetradymite ;—with silver 
(tellur-silber of G. Rose), from the Savodinskv mine, Altai, Siberia; — 
with lead (foliated tellurium, or nagyagite) ;—with silver and lead ( white 
and partly yellow tellurium, mullerine of Beudant);—with silver and 
gold ( graphic tellurium or schrift-ertz of authors; sylvanite, Haid.) ; all 
from Transylvania, where they occur in veins traversing greyw 7 acke and 
porphyry.— Native antimony from Allemont, Dauphiny, and the scarce 
antimonial silver or stibiuret of silver from the Hartz, &c. 
Case 4. Native arsenic (formerly called testaceous cobalt andscher- 
ben-cobalt), in reniform and botryoidal shapes, from Andreasberg, &c. ; 
and its chemical combinations (arseniurets)— with nickel (a variety of 
which is commonly called red or copper-nickel on account of its 
colour) ;— with cobalt (arsenical cobalt of authors partly), comprising 
the grey and part of the white cobalt of some mineralogists (to which 
probably belongs the bismuth-cob alt or kerstenite of some authors). 
In the opposite half of this Case are contained the substances be¬ 
longing to the orders of Carbon and of Selenium. To the former 
element are referred the diamond, anthracite, and graphite; to the 
latter the selenium metals or seleniurets. Among the specimens se¬ 
lected to illustrate the crystalline forms of the diamond are:—the 
primitive regular octahedron; the same with solid angles truncated; 
with edges truncated, forming the passage into the rhomb-dodecahedron ; 
varieties of the latter, giving rise to the six-sided prismatic and the 
tetrahedral forms ; cubes with truncated and bevelled edges; various 
hemitropic crystals or macles of diamonds; an octahedral diamond,* 
attached to alluvial gold; two others in a siliceous breccia with ce¬ 
ment of hydrous oxide of iron, and one in compact browm iron stone, 
from Brazil; models of large diamonds, &c. (with these are placed 
specimens of the alluvial rock in which this precious substance occurs 
in the East Indies and also in Brazil, where it is knowm by the name of 
cascalhao ;)—varieties of anthracite or kohlenblende (to which may be 
referred the Kilkenny coal), from various localities, with native silver 
from Kongsberg, &c. ;— graphite (commonly called black-lead), massive 
(the purest and most compact variety of which is that from Cumber¬ 
land), disseminated in porcelain earth, &c. 
Selenium : found in chemical combination with several metals; 
the seleniurets here deposited are: lead-seleniuret ( clausthalite, Beud.); 
—copper-lead-seleniuret;—mercury-seleniuret ( onofrite , Haid.) from 
D 
