(1) in glass-bulb. —­

  (2) in open tube.  Evolves SO^{2} and, when pulverized and gently
                         heated for some time is converted into CuO.

  (3) on charcoal.  Fuses to a bead, which spirts considerably and
                         gives off SO^{2}.  When pulverized and gently
                         roasted, is converted into CuO.

  (4) in forceps. —­

  (5) in borax.  The roasted mineral gives the copper reaction,
                         and sometimes also a slight iron-reaction.

  (6) in mic. salt.  As in borax.

  (7) with carb. soda.  In the reducing flame is decomposed, forming NaS
                         and metallic copper.  If the former be cut out
                         and laid upon silver, it gives the 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.