FLOOR.] 
MINERALS. 
47 
Petzite is the Silver (diargentous) telluride, Naumannite the corre- Div. II. 
spending selenide of Silver, while Argentite is the sulphide of Silver. Case 5 (i.) 
The latter are cubic in crystallisation, but the silver sulphide is a 
dimorphous mineral presenting itself as Acanthite in forms belonging 
to the orthorhombic system. To this system belongs also Copper- 
glance, a valuable ore of Copper, the " cuprous" (or dicupric) sulphide. 
Among the other important minerals in this section, a cubic series (^•) 
of monosulphides occurs which includes two commercially very im- 
portant ores — Galena, the lead sulphide, and Blende, the zinc ^^^^^^ ^'^^'^ 
sulphide. 
A Khombohedral series includes Covelliue, the cupric (monocupric) 
sulphide. Cinnabar, or mercuric sulphide, the unique ore of the ^^^^ ^ ^ ^' 
important metal Mercury. Millerite is the nickel monosulphide, and 
Greenockite, a rare mineral in bright yellow crystals, consists of the 
corresponding cadmium sulphide. 
There is also an important series of disulphides wherein Hauerite ^• 
and Iron-pyrites, which are severally the manganese and the iron 
disulphide, are cubic, while as Marcasite the latter compound is 
orthorhombic in crystallisation. These two forms of the iron disul- 
phide are frequent and familiar minerals, Iron-pyrites being con- 
spicuous for its sharply defined forms, and Marcasite, or "White Iron- 
pyrites," for the fantastic groupings in its crystallisation that have 
obtained for it the various names of Spear pyrites, Cockscomb 
pyrites, &c. 
Molybdenite (Mo S.^) and Realgar (Aso S^) are severally molybdenum Case 0. 
and arsenic disulphides ; the former a rhombohedral, the latter an 
oblique mineral. 
Here also is included Laurite, the rare ruthenium sulphide. 
Among the trisulphides we find some important compounds of the 
triad elements crystallising in the orthorhombic system. They are Case 9. 
Orpiment, or arsenic epideutosulphide (As^ S..), and the two isomor- 
phous epideutosulphides of Bismuth and Antimony, Bismuthite 
(Bi._, S.j) and Antimonite (Sbg S ,). Of both the last minerals, and in 
particular of Antimonite, very fine specimens are in this Table Case. 
Antimonite is an important source of the metal Antimony. 
The third section of the division is composed of minerals wherein cer- Sect. iii. 
tain arsenides, &c., of Section i. are combined with sulphides of Section 
ii., or which may be looked on as the result of a replacement of half 
the Arsenic of the minerals in the former section, by its equivalent of 
Sulphur. Of these there is a cubic series, including Cobaltine, or ^--^ 
Cobalt-glance, the " Silver White Cobalt" of early mineralogists, a 
Cobalt arseno-sulphide, Co (As^ , S); or Co As^; Co S. In Gersdorf- 
fite, or Nickel-glance, and Ullmannite or Antiraonial Kickel-glance, 
half the sulphur in a nickel disulphide is replaced by Arsenic and 
by Antimony respectively. 
In this section, also, the minerals of this chemical type exhibit a 
dimorphism similar to that of Pyrites and Marcasite among the disul- 
phides of Section ii., and of Eammelsbergite and Chloanthite among 
the diarsenides of Section i. ; for in Mispickel and Glaucodote we ^^^se 10. 
