| Description |
Reddish metal, malleable and ductile, with high electrical
and thermal conductivities. Resistant to air and water but slowly weathers
to green patina of basic carbonates. (Historically important alloy,
bronze.) Used as wire for conducting electricity; coins; alloys, etc. Diagnostic tests:
On charcoal alone, or better with soda (Na2CO3),
metallic copper can be reduced from most of its compounds. In the case of
sulfides the powdered mineral is first roasted before adding the
soda.
With the borax bead test, it gives a green bead when hot, becoming blue
when cold.
In solution, copper chloride gives a vivid blue flame test. Roasted ores
and non-sulfide copper minerals will give the blue flame by adding HCl to
the sample before heating.
In solution, the addition of excess amounts of NH4OH will
produce an intense blue color to the sample.
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