The world runs on rock · Story 11 of 12

The Screen the rare elements in a phone

A phone is a sandwich of glass, metal and silicon a few millimetres thick. When scientists at the University of Plymouth ground one up, they found at least 39 elements inside.¹

Scroll to take a phone apart

Night photo from orbit of Hong Kong and Shenzhen: white and orange city lights wrapped around a dark harbour — Hong Kong (bottom centre) and Shenzhen at night from the International Space Station, 20 December 2024. NASA (public domain).

Where phones are made

A city of electronics

Shenzhen grew from a small town into one of the world's great electronics manufacturing centres after it became China's first special economic zone in 1980.² The metals that go into its phones come from mines on every continent but Antarctica.

Take it apart

Eight layers

This is a typical modern phone, not any one model, pulled apart from front to back.

Cover glass toughened aluminosilicate glass on many phones³
Touch layer a grid of transparent conductor
Display a glass panel of red, green and blue pixels
Frame aluminium or steel
Board chips, capacitors and solder
Vibration motor with a small magnet
Battery lithium-ion

The board

Tin, tantalum, gold

Chips are held on with solder, one of tin's main uses. Next to them sit tiny capacitors; tantalum is used in some of the smallest and most stable, and aluminium, ceramics and niobium in others.⁴

SnTaAuCuSi

The front

Glass that conducts

The touch layer and the display need electrodes you can see through. For decades the answer has been a film of indium tin oxide, and it takes most of the indium the world uses.⁵

Indium tin oxide

A clear metal film

Indium oxide is a clear crystal. Swap about one indium atom in ten for tin and each tin gives up a spare electron, so the film conducts while light still passes through. The model is a sketch, not the real crystal structure.⁶

Where it goes

The USGS says ITO coatings are used mainly as conductors in flat-panel displays, most of them liquid crystal displays, and that making ITO remains most of the world's indium demand.⁵

InSnO

Could it be replaced?

Researchers have tried silver and copper nanowires, carbon nanotubes, graphene and antimony tin oxide in its place.⁵ Refined indium was about $350,000 a tonne in 2025, by the USGS estimate.

Follow the supply

1 · Indium

Indium is mostly recovered from the zinc ore sphalerite, at up to 100 parts per million. China produced 69% of refined indium in 2025 and South Korea 16%. In February 2025 China put indium under export restrictions, and exports of unwrought indium fell 72% between September 2024 and September 2025, as reported by Asian Metal.⁵

2 · Tin

China mined 24% of the world's tin in 2025 and Indonesia 21%.⁴ Two halts show how thin the rest can be:

Aug 2023The Wa State authorities in Myanmar suspended all mining in their area. Wa had supplied over 70% of Myanmar's tin.⁷ Myanmar's output fell from about 20,000 tonnes in 2024 to 12,000 in 2025.⁴
13 Mar 2025Alphamin halted Bisie in eastern DR Congo, reported as the world's third-largest tin mine, as M23 rebels advanced.⁸
9 Apr 2025Bisie began restarting in phases, and the tin price fell back.⁹

3 · Tantalum

DR Congo mined 52% of the world's tantalum in 2025 and Rwanda 16%.⁴ In June 2025 the two governments signed a US-mediated peace agreement that the USGS said, if sustained, could steady the region's mineral trade.⁴

Satellite map view of the Nyiragongo volcano above the city of Goma and the blue water of Lake Kivu, with recent lava flows

Goma and Lake Kivu, eastern DR Congo, after the 2002 Nyiragongo eruption, from Landsat, ASTER and SRTM data. NASA/JPL/NIMA (public domain).

Conflict minerals

The 3TG rules

Tin, tantalum, tungsten and gold are known together as 3TG. Since 2012 a US rule under the Dodd-Frank Act has made companies that file with the SEC report whether their products contain 3TG from DR Congo and its neighbours. Since 1 January 2021 an EU regulation has required importers of these metals to check their supply chains.¹⁰

Why "critical"

Small amounts, few sources

A phone holds only grams of most of these metals, but billions are made, and several of the metals come from one country or one troubled region.

InIndiumChina 69% SnTinChina 24% TaTantalumDR Congo 52% AuGoldcontacts CoCobaltDR Congo 74% LiLithiumAustralia 32% NdRare earthsvibration motor, speakers GaGalliumchargers, radio chips

Take your own phone apart, element by element, and follow each metal back to where it was likely mined: What's in your phone.

Next, the finale: The Map, who holds the world's mineral chokepoints. Before this: The Grid, The Engine, The Body, The Shield, The Signal, The Rocket, The Magnet, The Battery, The Mind and The Chip.

Sources

Shares of world output are from USGS Mineral Commodity Summaries 2026 via our minerals data. The 3D models are illustrations, not engineering drawings or any one product. Photos: NASA, public domain.