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  1. As a Mineral: Occurs in Pinal County. Common in Arizona.

Chemical Formula: Cu

Specific Gravity: 8.9

Luster: Metallic

Hardness: 2.5-3

Copper is a chemical element and not a mineral in the traditional sense. It is a reddish-brown metal with a metallic Luster and is widely used in various applications.

Next Pinal County mineral: Coquimbite

2. As an Element

Chemical Symbol: Cu

Atomic Number: 29

Atomic Mass: 63.546 g/mol Known since ancient times.

Copper is a metallic native mineral, with the chemical symbol Cu. It is a soft, malleable, and ductile metal that humans have used for thousands of years.

Copper has a reddish-orange color. It is an excellent conductor of both electricity and heat, as anyone who’s dealt with electric wires or copper-bottomed cookware probably knows. It is a vital component in many industrial applications and has played a crucial role in the development of human civilization around the world.

Copper was one of the first metals used by humans. Archaeologists have found artifacts made of copper dating back to 9000 BC in modern-day Iraq, and the Egyptians used copper as early as 2600 BC. In ancient times, copper was primarily used to make weapons, tools, and jewelry.

Once copper ore is extracted from a mine, the metal is refined and processed into various forms, including wire, tubes, sheets, and alloys.

Uses of Copper

A major property of copper is its excellent conductivity. It is the second-best conductor of electricity after silver, making it an essential component in the electrical and electronics industries. Copper is used in electrical wiring, power generation, and transmission, as well as in electronic devices such as computers, smartphones, and televisions. Copper is much more abundant, and so much less expensive (valuable) than silver, which is why copper is used.

Copper is vital in the construction industry. It is used in plumbing, roofing, heating, and cooling systems. Copper has antimicrobial properties that make it an ideal material for medical facilities, where it is used in everything from hospital beds to door handles. It’s also woven into fabrics, though the claims made in popular commercials about its benefits are not fully substantiated.

Copper is also used in the production of coins and artwork. The metal used to be used for many low-value coins, but it has become so much more useful in electronics that today, the United States penny is made of 97.5% zinc and 2.5% copper. Many other countries have also used copper in their coinage. Copper’s malleability and ductility make it an ideal material for sculptors and artists, who use it to create intricate designs and sculptures.

The U.S. all-copper penny was replaced with a zinc-based coin in 1982. Before that, the penny was made of 95% copper and 5% zinc. Rising copper prices made it more expensive to produce. To reduce costs, the U.S. Mint switched to the new composition. The zinc-based composition is used for the basic coin, with a thin layer of copper on the outside to maintain its traditional appearance. It still costs 2.72 cents to produce a penny, but this switch reduced that.

In recent years, copper has gained attention for its use in renewable energy technologies. Copper is used in the production of solar panels, wind turbines, and electric cars. The growing demand for renewable energy sources has led to an increase in copper prices, making it a more valuable commodity, leading to the reopening of several mines in Arizona and elsewhere that had been previously closed when copper was much less valuable.

Copper Mining

There are two main types of copper mining: open-pit mining and underground mining.

Copper is mined worldwide. The top copper-producing countries are Chile, Peru, China, the United States, and the Democratic Republic of Congo.

Open-pit mining, or surface mining, involves digging a large open pit to extract copper ore. The ore is extracted using heavy machinery and transported to a processing plant, sometimes at least partially on the mine site. This method is commonly used in areas where the copper ore is located near the surface and is relatively easy to extract.

Bingham Canyon Mine, Utah, is the largest man-made excavation ever, and deepest open-pit mine in the world. Satellite image May 2, 2013. NASA Earth Observatory image

Underground mining involves digging shafts and tunnels deep beneath the earth’s surface to reach the copper ore. This method is used when the copper ore is located deeper underground and requires more extensive and costly excavation. In underground mining, workers extract the copper ore using drills, explosives, and other heavy equipment, then transport it to the surface for processing.

There are several variations of underground mining, including block caving, room and pillar mining, and longwall mining. Block caving involves undercutting the ore body and allowing it to collapse under its weight, while room and pillar mining involves leaving pillars of rock to support the mine roof. Longwall mining uses a continuous mining machine to extract the ore in a long wall of ore.

A newer technology, in situ mining is being tried in several places. One of those is by Florence Copper (a sponsor of the Museum), in Florence, Pinal County, Arizona. They force fluid into the rock in an area. That fluid dissolves the copper from the ore while still underground, where it is flushed to vacuums that bring it to the surface for refining. The technique can only be used in a few places, under specific geological conditions. After the copper is extracted, the land can be quickly returned to other uses.

Each type of mining has advantages and disadvantages. Open-pit mining is typically less expensive and less hazardous for workers, but it can have a significant environmental impact, including soil and water pollution. Underground mining is more expensive and presents more risks to workers but is generally less damaging to the environment. The choice of mining method depends on a variety of factors, including the location of the ore, the size of the deposit, and the economic viability of each method.

The Copper Age

The Copper Age, also known as the Chalcolithic period, was an era characterized by the widespread use of copper tools and weapons. In Europe and Asia, it occurred between 7000 to 5000 years ago, between the Neolithic and Bronze Ages.

White Temple ziggurat in Uruk, one of the first cities, was built during the Copper Age about 5000 years ago. Photo by Tobeytravels

The New World Copper Age’s impact in North America was less pronounced. Nonetheless, recent archaeological discoveries have shed new light on the role of copper in the ancient cultures of North America.

The Copper Age in North America is generally thought to have begun around 4000 BCE and lasted until the arrival of Europeans in the late 15th century CE. Copper artifacts from this era have been found throughout the continent, from the Great Lakes region to the Southwest.

The Great Lakes region, in particular, was a significant center of copper production and use during this time. The Keweenaw Peninsula, the northernmost part of the Upper Penninsula of Michigan was one of the most abundant sources of copper in North America, and the indigenous peoples of the region developed sophisticated mining techniques to extract the metal.

Map of the location of the Keweenaw Penninsula by Phizzy at the English Wikipedia

Much of the great lakes copper is native, meaning it is fairly pure and doesn’t need processing to be used. This meant the indigenous people didn’t need to invent smelting, which is the technology that led to the Bronze and Iron ages in the eastern hemisphere.

They fashioned copper into a variety of tools, including knives, spearheads, and axes, as well as decorative objects such as beads and bracelets.

Copper Age tools from Wisconsin Copper Culture State Park. Photo Yinan Chen

The Hopewell culture, which flourished in the Ohio River Valley between 200 BCE and 500 CE, was also known for its use of copper. The Hopewell people traded copper objects over long distances and fashioned them into intricate jewelry and decorative pieces. Copper artifacts have also been found in the ancient cultures of the Mississippi River Valley, the Southwest, and the Pacific Northwest.

Map of the greater Hopewell cultural area by Heironymous Rowe

The use of copper in North America declined after the arrival of Europeans, who brought with them new materials and technologies. However, copper remained an important resource in some indigenous cultures, including the Inuit people of Alaska and Canada, who used copper to fashion knives, harpoons, and other tools.

Despite its limited role in North American history, the Copper Age had a profound impact on human development worldwide. The use of copper allowed for the development of more efficient tools and weapons, which in turn facilitated the growth of agriculture, trade, and other complex societies.

In recent years, interest in the Copper Age has grown, and archaeologists have made significant discoveries about the use of copper in ancient North America. These discoveries have expanded our understanding of the role of copper in the development of human societies and shed new light on the history of North America before the arrival of Europeans.

In Arizona, the use of copper dates back thousands of years. Copper was a valuable resource for local cultures, as it could be fashioned into a wide range of tools and objects.

Copper was commonly used to create jewelry, such as earrings, necklaces, and bracelets, often decorated with turquoise, shells, and other materials.

Copper was also used to make a variety of tools, including knives, axes, and hoes. Copper-tipped arrows were used for hunting and warfare, and copper spearheads were also used.

Copper objects played an important role in religious and ceremonial practices. For example, copper rattles were used in healing ceremonies, and copper objects were often buried with the dead as offerings.

Copper was a valuable commodity for trade, and Native peoples in Arizona traded copper objects with neighboring cultures. Archaeologists have found evidence of long-distance trade networks that extended throughout the Southwest. Copper objects were often used as status symbols, indicating the wealth and social standing of an individual or group. Larger copper objects, such as bells and headdresses, were particularly prestigious.