Page 5 - Curriculum Visions Dynamic Book

When scientists calculate the most abundant metals in the world, they add up the metal content in rocks as well as native metals. On
this basis the most common metal is aluminium, followed by iron, calcium, sodium, potassium, and magnesium. Gold is near the bottom of such a list.
When metals are found combined with other substances in rocks, they may add colour or some other property to the rock. However, in general, the amount of a metal in a rock is very small. Those rocks that do contain enough metal to make it worth mining for the metal are called metal ores, or just ores.
(Below) Open-pit mining
of copper ore in one of
the world’s biggest mines
at Morenci in Arizona. Copper compounds can
give a strong green colour
to ores such as the copper silicate sample shown below, which is called crysocolla (Cu2H2Si2O5(OH)4). The mine rock in this picture, however, is mainly brown because iron oxide is the main metal in the ore. Separating the copper from its ore and other ores is a very costly process.
(Left) Haematite (iron ore) contains a large proportion of iron in the form of iron oxide (Fe2O3). The reddish-brown colour is a sign of the iron.
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