(8) Special reactions. --
Mineral. Dioptase
Formula. [.Cu]^{3}[...Si]^{2} + 3[.H].
Behavior
(1) in gla.s.s-bulb. Gives off water and turns black.
(2) in open tube. --
(3) on charcoal. In the oxidizing flame becomes black. In the reducing flame red.
(4) in forceps. V. Colors the outer flame intensely green.
(5) in borax. Gives the copper reactions.
(6) in mic. salt. As with borax. The silica remains undissolved.
(7) with carb. soda. With a small quant.i.ty of carbonate of soda fuses to a bead, which on cooling is opaque and has a red fracture. With more alkali forms a slag, containing little beads of reduced copper.
(8) Special reactions. --
Mineral. Malachite
Formula. [.Cu]^{2}[..C] + [.H].
Behavior
(1) in gla.s.s-bulb. Gives off water and turns black.
(2) in open tube. --
(3) on charcoal. Fuses to a bead with a strong flame is reduced to metallic copper.
(4) in forceps. Fuses and colors the outer flame brilliantly green.
(5) in borax. Gives the copper reaction.
(6) in mic. salt. As with borax.
(7) with carb. soda. Yields metallic copper.
(8) Special reactions. Dissolves in HCl with much effervescence.
Mineral. Blue vitriol
Formula. [.Cu][...S] + 5[.H].
Behavior
(1) in gla.s.s-bulb. Intumesces, gives off water and becomes white.
(2) in open tube. Strongly heated is decomposed, given off SO^{2} and being converted into CuO.
(3) on charcoal. As in the gla.s.s-bulb. Then fuses, coloring the outer flame green, and is reduced to metallic copper and [,Cu=].
(4) in forceps. Fuses and colors the outer flame blue.
(5) in borax. The roasted mineral gives copper reaction.
(6) in mic. salt. As in borax.
(7) with carb. soda. Yields metallic copper. The alkaline ma.s.s laid on silver gives S reaction.
(8) Special reactions. Gives the sulphuric acid reaction.
Mineral. Libethenite
Formula. [.Cu]^{4}[.....P] + 2[.H].
Behavior
(1) in gla.s.s-bulb. Gives off water and turns black.
(2) in open tube. --
(3) on charcoal. Gradually heated, turns black and fuses to a bead, having a core of metallic copper.
(4) in forceps. Fuses but does not color the flame distinctly. On cooling is black and crystalline.
(5) in borax. Gives the copper reaction.
(6) in mic. salt. As in borax.