Refined Indium (1 kg ingot)

Overview

Indium is a soft, silvery metal that melts just above the boiling point of water. Almost nobody buys indium as indium: it is bought as the transparent conductive coating on every touchscreen, as the substrate under the lasers in fiber-optic transceivers, and as the low-melt solders and seals inside electronics. World production is under 1,000 tonnes a year, a single mid-size copper mine moves more metal in a day.

A byproduct metal

There are no indium mines. The metal substitutes into the crystal lattice of Sphalerite Zinc Ore at ten to a hundred parts per million, so it enters the economy only when zinc is mined and smelted. During roasting and leaching of Zinc Flotation Concentrate, the indium concentrates into Zinc Smelter Flue Dust / Leach Residue and leach residues. A smelter that processes those residues recovers indium; one that does not sends it to tailings. This is why indium supply cannot respond quickly to price: producing more of it means building recovery circuits at zinc smelters, not opening indium mines.

The recovery chain on this page follows one kilogram of refined metal: roughly forty tonnes of mined ore and twenty tonnes of concentrate pass through a smelter to yield it. The residues are leached in sulfuric acid (Sulfuric Acid Leach Liquor), the indium is pulled out selectively by Solvent Extraction Circuit with DEHPA, displaced onto aluminium as Sponge Indium, cast into Crude Indium Anodes, and electrorefined to 99.995% or better in an Electrorefining Cell.

Why it is a chokepoint

China refines about 70% of the world's indium, a consequence of operating the largest zinc-smelting industry and equipping it with recovery circuits. In February 2025 China placed export controls on indium phosphide, the compound semiconductor grown from this metal, see Indium Phosphide Wafer for that chain and why data-center optics depend on it. The remaining production is spread across smelters in South Korea, Japan, Canada, Belgium, and Peru, and a meaningful share of supply now comes from recycling spent ITO sputtering targets, which lose most of their material to overspray rather than to the coated glass.

Where it goes

About seventy percent of demand is indium tin oxide for displays and touch sensors, the Smartphone page traces roughly 30 mg of indium into one phone through its ITO layers. The fastest-growing use is Indium Phosphide Wafer substrates for photonics. The rest is low-melting alloys and solders, semiconductor bonding, and control rods.