White copper has the highest hardness and red copper has the best conductivity. Brass is an alloy of copper and zinc, hence its yellow color. Brass has good mechanical properties and wear resistance, and can be used to manufacture precision instruments, ship parts, artillery shells and so on. Brass sounds good, so gongs, cymbals, bells and horns are all made of brass.

The alloy of copper and tin is called bronze, which is named after its blue color. It was a common alloy in ancient times (such as the Bronze Age in China). Bronze generally has good corrosion resistance, wear resistance, castability and excellent mechanical properties.

It is used to manufacture precision bearings, high-pressure bearings, seawater corrosion-resistant mechanical parts on ships and various plates, pipes and bars. Bronze also has an abnormal feature-"thermal contraction and cold expansion", which is used to cast statues. Expansion after cooling can make eyebrows clearer.

Extended data:

The hardness value is not an absolute hardness value, but a value expressed in the order of hardness. When applied, hardness is determined by scoring comparison. If a mineral can scrape calcite but not fluorite, its Mohs hardness is 3 ~ 4, and so on.

Mohs hardness is only relative hardness, which is rough. The hardness of hydrotalcite is 1, that of diamond is 10, and that of corundum is 9, but the absolute hardness measured by microhardness tester is 4 192 times that of talc, and that of corundum is 442 times that of talc. Mohs hardness is easy to apply and is often used in field work. For example, nail hardness is about 2.5, copper coins are 3.5-4, steel knives are 5.5, and glass is 6.5.

In addition to the original list of 1~ 10 minerals, hardness values of other commonly used items are also collected here for reference.

Baidu encyclopedia-Mohs hardness