Identity

Formula Cu
Class Native Elements
Crystal System Cubic
Hardness 2.5-3
Color Copper-red, tarnishing brown to green
Lustre Metallic
Specific Gravity 8.9
Cleavage None
Streak Metallic copper-red
Technical notes (click to open)(click to close)
Identity A native element, the pure metal; the IMA name is simply copper
Habit Branching, wiry, and plate like growths, with twinned crystals; sharp single crystals are rare
Tarnish Bright red when fresh, weathering to brown and then the green of malachite and azurite
Occurrence In old basalt flows and the oxidized zones of copper deposits, with cuprite, malachite, and silver
Record mass The largest single mass found weighed about 420 tons, from Michigan

Name & Human History

Etymology

Copper is one of the oldest friends of the human race. It is one of the very few metals that nature offers in pure, ready to use form, as native copper. Its name traces back to the island of Cyprus, a great source of copper in the ancient Mediterranean. The Romans called it the metal of Cyprus, which in Latin became cuprum, the root of both the word copper and its chemical symbol.

Through the Ages

Copper changed the course of history. It was one of the first metals people ever worked, soft enough to hammer into tools and ornaments without any furnace. Later, smiths learned that mixing copper with a little tin made bronze, a far harder metal, and the Bronze Age was born. Today copper still runs the modern world, carrying electricity through the wires in nearly every building and device.

Geology & Occurrence

Formation

Native copper forms where copper rich fluids meet the right conditions underground, often in old lava flows and in the weathered tops of copper deposits. It can grow in beautiful branching, tree like shapes, or as twisted wires and thin sheets. Fresh copper has a bright reddish shine, but in air it slowly tarnishes to brown, then to the familiar green of an old roof or statue.

Notable Localities

The greatest native copper deposits on Earth lie in the Keweenaw Peninsula of Michigan, on the shore of Lake Superior. Native peoples mined copper there for thousands of years. The largest single mass ever found weighed about 420 tons. Fine copper crystals also come from Arizona, from Bolivia, and from the old mines of Cornwall in England.

Did you know?

One reason copper has served humans for so long is that you can simply find it. Most metals are locked inside ores and must be smelted out with heat. But native copper sits in the ground as the pure metal, soft and bendable. An early human could pick up a lump and hammer it into a knife or a bead with nothing but a stone. That head start helped copper lift humanity out of the Stone Age.

Filter by: ·