sulfur
reaction.

(8) Special reactions. --

* * * * *

Mineral. Copper pyrites

Formula. [,Cu=][,,,Fe=].

Behavior

(1) in glass-bulb. Decrepitates, sometimes gives a sublimate of
sulphur and becomes bronze colored on the
surface.

(2) in open tube. Evolves SO^{2} and is finally converted into a
dark red mixture of Fe^{2}O^{3} and CuO.

(3) on charcoal. Fuses readily with much ebullition and is
magnetic on cooling.

(4) in forceps. --

(5) in borax. As the preceding; but when the copper has been
removed by reducing on charcoal, the bead shows
a strong iron color.

(6) in mic. salt. As the preceding, but the color in the oxidizing
flame is green, owing to the presence of iron.

(7) with carb. soda. Yields a bead of metallic copper and some
magnetic oxide of iron which remains on the
charcoal. The fused gives a sulphur reaction on
silver.

(8) Special reactions. --

* * * * *

Mineral. Fahlerz

Formula. ([,Cu=][,Ag][,Fe][,Zn])^{4} ([,,,Sb][,,,As]).

Behavior

(1) in glass-bulb. Sometimes decrepitates, fuses, and when very
strongly heated, gives a red sublimate of
[,,,Sb] with [...Sb], also sometimes a black
sublimate of [,Hg] and occasionally [,,,As].

(2) in open tube. Fuses and gives off thick fumes of SbO^{3} and
SO^{2}, also generally AsO^{3}, leaving a black
infusible residue. If Hg be present, it is
sublimed and condenses in the tube in small
drops.

(3) on charcoal. Fuses to a bead, which fumes strongly and
incrusts the charcoal with SbO^{3}, and
sometimes ZnO, which cannot be volatilized.
Emits a strong smell of arsenic.

(4) in forceps. --

(5) in borax. The residue obtained on charcoal thoroughly
roasted gives a copper react