Indium is the softest metal on Earth

Indium is the softest metal on Earth, a rare metal formed by processing zinc ore and combining it with iron, lead, and copper ore. One interesting thing about indium is that when it bends, it makes a sound like crying.

Indium was discovered in 1863 by Ferdinand Reich of the Freiberg Institute of Mining in Germany. Reich was studying a brown sparkling mineral containing zinc (now known as sphalerite, ZnS), which he believed may contain the recently discovered element thallium. He obtained a yellow precipitate from it, which he thought was thallium sulfide, but the line displayed by its atomic spectrum was not thallium. However, as he was color blind, he asked Hieronymous Richter to help him check the spectrum, and he noticed a brilliant violet line, which ultimately gave him the name indium.

Important features: white, soft material, with conductivity

Main producing countries: China, Japan, South Korea

Important use: Indium is most commonly used in products such as alloys, solder, and soft metal high vacuum seals in the semiconductor industry. During World War II, it was used to coat bearings on aircraft engines, but now it is used to manufacture more corrosion-resistant mirrors.