Treasures of the Earth

Smithsonian, Washington D.C.

A deep-blue diamond that glows red under ultraviolet light and carries a legendary "curse." Boron atoms trapped in its carbon give it the rare blue colour.

British Crown Jewels, London

The largest gem-quality rough diamond ever found, unearthed in South Africa in 1905 and cut into nine major stones — the biggest, the Great Star of Africa, sits in the Sovereign's Sceptre.

American Museum of Natural History, New York

One of the largest star sapphires in the world, around two billion years old. Tiny needle-like crystals inside scatter light into a glowing six-rayed star.

Crown Jewels, Tower of London

A diamond with a turbulent history across South Asia and Persia before reaching the British crown. Its name means "Mountain of Light" in Persian.

Imperial State Crown, London

For centuries this great red gem in the British crown was thought to be a ruby — but it is actually a spinel, a different mineral that fooled jewellers for ages.

Smithsonian, Washington D.C.

One of the largest faceted blue sapphires on display anywhere — roughly the size of a chicken egg — mined in Sri Lanka and framed by 20 diamonds.

Made of: Marine limestone & shale

The summit is marine limestone full of sea-creature fossils — rock that formed on an ancient ocean floor and was lifted 8.8 km up as India crashed into Asia. Lower slopes are metamorphic rock and granite.

Made of: Granite

A colossal dome of granite in Yosemite, formed from magma that cooled deep underground, then exposed and sheared on one side by grinding Ice Age glaciers.

Made of: Gneiss

This iconic pyramid peak is built of gneiss. Remarkably, its very top is a slice of the African tectonic plate, thrust over European rock when the two collided to raise the Alps.

Made of: Arkose sandstone

A single immense block of arkose sandstone standing above the desert. Its glowing red surface is iron minerals that have rusted; inside, the rock is grey.

Made of: Basalt columns

Around 40,000 interlocking hexagonal columns of basalt, formed about 60 million years ago when a thick lava flow cooled and cracked into neat geometric pillars.

Made of: Dolomite & limestone

Pale peaks built from an ancient fossil coral reef, now the mineral dolomite. At sunset they blaze pink and orange — a glow the locals call enrosadira.

Made of: Granite

The four presidents are carved into fine Harney Peak granite, chosen because it is hard, uniform and erodes only about 2.5 cm every 10,000 years.

Made of: Quartzitic sandstone

Its famous flat top is hard quartzitic sandstone over 450 million years old — far older than the dinosaurs — resting on a base of granite and slate.

Made of: Basaltic & andesitic lava

A classic stratovolcano built up in layers of basaltic and andesitic lava and ash from repeated eruptions over tens of thousands of years.

Made of: Quartz sandstone

Thousands of towering quartz-sandstone pillars, carved by erosion along natural cracks — the inspiration for the floating mountains in the film Avatar.

Made of: Granite & gneiss

A rounded dome of granite and gneiss rising straight from the sea at Rio de Janeiro, smoothed over millions of years into its loaf-like shape.

Made of: Granite (monzogranite)

One of the largest exposed masses of granite on Earth, a huge rounded dome in Georgia formed from magma that solidified deep underground and was later exposed.

Made of: Granite

A sheer wall of granite rising about 900 metres from the Yosemite Valley floor — one of the most famous rock-climbing challenges in the world.

Made of: Phonolite porphyry

A dramatic flat-topped tower of igneous phonolite porphyry, cracked into giant vertical columns as the molten rock cooled underground, then exposed by erosion.

Made of: Granite & andesite lava

Britain's highest peak is the eroded root of an ancient collapsed volcano, with a summit of dark andesite lava sitting inside a ring of granite.

Made of: Conglomerate

Enormous rounded pillars of conglomerate — a natural concrete of pebbles and sand — topped by centuries-old monasteries perched impossibly on the summits.

Made of: Granite

The highest peak in the Alps is built around a huge dome of pale granite that cooled deep underground, then was shoved skyward and carved by glaciers into sharp spires and needles (aiguilles).

Made of: Volcanic rock (trachyte & basalt)

Africa's tallest mountain is a giant dormant volcano made of layer upon layer of lava and ash. Its iconic snow-cap sits almost on the equator, atop solidified trachyte and basalt lava flows.

Made of: Basaltic lava

Europe's most active volcano, endlessly rebuilding itself from fresh basaltic lava. Each eruption adds new black rock to its slopes, making Etna one of the youngest-surfaced mountains on Earth.

Made of: Granite

The famous pale towers are granite that cooled underground about 12 million years ago, then was exposed by erosion — still capped with dark crumbly sedimentary rock, giving each tower a two-tone look.

Made of: Quartz sandstone

A vast flat-topped tepui of ancient quartz sandstone, nearly two billion years old. Its sheer cliffs rise straight out of the rainforest, leaving a lost-world plateau on top.

Made of: Greywacke sandstone

New Zealand's highest peak is made of greywacke — a tough, grey sandstone laid down on an ancient sea floor, then crumpled upward along the plate boundary that still lifts the Southern Alps today.

Made of: Limestone

The mythical home of the Greek gods is built of thick layers of limestone — hardened ancient sea-floor sediment — uplifted and weathered into deep gorges and steep summits.

Made of: Gneiss

One of the world's highest mountains, built of gneiss that is being squeezed upward astonishingly fast as India drives into Asia — the rock here rises several millimetres every year.

Made of: Slate, schist & gneiss

Ancient, worn-down Appalachian peaks of metamorphic slate, schist and gneiss — rock heated and squeezed when continents collided hundreds of millions of years ago, now softened into forested ridges.

Made of: Gneiss

A sacred Chinese mountain resting on some of the oldest rock in eastern Asia — Taishan gneiss around 2.5 billion years old, from the very foundations of the continent.