40 Fun Facts About Obsidian

In Game of Thrones, obsidian that can destroy White Walkers is better known by which name?

Dragonglass is the Westeros name for obsidian, and Samwell Tarly proves its power in A Storm of Swords by killing one of the creatures with a dagger made of it.

Which Egyptian pharaoh's golden funerary mask has quartz eyes fitted with pupils of obsidian?

Tutankhamun's mask pairs its obsidian pupils with eyebrows and eye surrounds of blue lapis lazuli, all set into about ten kilograms of gold.

Where in the Pacific do giant stone statues have sockets made to hold white coral eyes with obsidian pupils?

Easter Island's moai kept the secret until 1979, when archaeologists pieced together broken white coral and realised the empty sockets were built to hold eyes.

In Minecraft, a frame of obsidian blocks becomes the portal to which dimension?

The Nether is made mostly of lava, a fitting place to reach through a doorway of obsidian, since the real rock is itself born from lava.

Conquistadors reported obsidian-edged swords killing which animal with a single blow to the neck?

Horse and rider were both at risk: Bernal Díaz del Castillo described warriors slashing at a cavalryman's mare and cutting her head off at the neck.

John Dee is said to have used an Aztec obsidian mirror to summon spirits while advising which English queen?

Elizabeth I kept Dee as her court astronomer, and the mirror linked to him, an Aztec piece brought to Europe in the late 1520s, is now in a London museum.

Obsidian flakes to an edge far finer than steel, so surgeons have tested it in which tool?

Scalpels with obsidian blades can have a cutting edge only about three nanometres thick, but the glass is brittle and the blades break very easily.

Obsidian Cliff, quarried by Native Americans for some 12,000 years, stands in which US national park?

Yellowstone's Obsidian Cliff formed from a thick lava flow about 180,000 years ago, and its roadside kiosk was the first wayside exhibit in the national park system.

Which name is given to small rounded obsidian pebbles, after a legend of grieving families in Arizona?

Apache tears take their name from a story in which outnumbered warriors chose death over defeat, and the tears of their families turned to stone where they fell.

Which frothy volcanic rock, light enough to float, is found alongside obsidian in the same lava flows?

Pumice is a glass too, frothed by escaping gas like a freshly opened fizzy drink, so a single flow can be solid obsidian at its base and foam at the top.

What was the Aztec wooden sword edged with rows of razor-sharp obsidian blades called?

Macuahuitl means hand-wood in Nahuatl, and the weapon's glass edges were sharper than steel razors yet tended to shatter against Spanish armour.

Which Aztec god of the night sky and sorcery has a name usually translated as Smoking Mirror?

Tezcatlipoca is often shown with an obsidian mirror where one foot should be, a reminder of the creation myth in which he lost it to the earth monster Cipactli.

Which speckled countertop rock shares obsidian's chemistry but cooled slowly, deep underground, into large crystals?

Granite and obsidian can come from the same magma: left to cool slowly it grows visible crystals, but chilled fast at the surface it freezes into glass.

Obsidian is born from cooling lava, which places it in which of the main families of rock?

Igneous rocks form from molten material, yet obsidian rarely lasts: the glass slowly crystallises into ordinary stone, so little of it is older than the Miocene epoch.

Which lightweight white granules in potting soil are made by heating a rock that began as obsidian?

Perlite swells to as much as 16 times its size when heated, puffing up so dramatically that Popular Mechanics called it volcanic popcorn in 1954.

Archaeologists date obsidian tools by measuring a thin rind that grows as the glass absorbs what?

Water creeps into a freshly broken obsidian surface at a rate that can be measured, so the thickness of the rind works like a clock that started when the tool was chipped.

The oldest known manufactured mirrors, polished obsidian from around 6000 BCE, were found in which modern country?

Turkey's Stone Age town of Çatalhöyük yielded the mirrors, and its people also chipped obsidian into blades, daggers and sickles.

Some of the earliest known obsidian tools, Stone Age handaxes, come from Kariandusi in which African country?

Kenya's Kariandusi site sits on the edge of the Great Rift Valley, and its handaxes were probably made by Homo erectus, long before our own species appeared.

Obsidian carried more than 1,500 miles from the Rocky Mountains was buried in Hopewell mounds in which state?

Ohio's Hopewell people buried hundreds of pounds of the volcanic glass in their mounds, and may have made the long journey west to fetch it themselves.

Apollo astronauts trained at Newberry Volcano, home of the hikeable Big Obsidian Flow, in which US state?

Oregon's Big Obsidian Flow is only about 1,300 years old, the youngest lava on Newberry Volcano, and NASA sent crews there in the 1960s to practise reading volcanic terrain.

Which Roman author's Natural History says obsidian was first found in Ethiopia by a Roman traveller?

Pliny the Elder named the finder Obsius, and the modern word rests on a copying slip that turned the Latin obsianus into obsidianus.

Obsidian from Pachuca in central Mexico was prized across Mesoamerica for which unusual colour?

Green obsidian with a golden tint came from the Pachuca quarries, and a scraper made of it has turned up as far away as Oklahoma.

The Aztec goddess Itzpapalotl has a name usually translated as the obsidian form of which winged creature?

Butterfly sounds gentle, but Itzpapalotl was a fearsome warrior goddess, pictured with a skeletal head and wings tipped with stone blades.

Stone Age sailors crossed the Aegean to collect obsidian from which Greek island, later famed for a Venus statue?

Milos obsidian reached a mainland cave around 13,000 BC, the earliest evidence of seafaring by modern humans in Greece.

Which glassy pebbles, now linked to meteorite impacts, were once thought to be obsidian erupted from the Moon?

Tektites had a NASA scientist arguing for a lunar origin into the 1990s, but their chemistry shows they were melted from Earth's own crust.

What is the craft of striking flakes from obsidian or flint to shape blades and arrowheads called?

Knapping was revived in the 20th century by experimenters such as Don Crabtree, who taught himself to copy ancient obsidian blades by studying the chips their makers left behind.

Which term describes the smooth, curved surfaces left when obsidian or thick glass breaks?

Conchoidal fracture leaves ripples like the growth lines on a seashell, and it happens because glass has no natural planes to split along.

Obsidian is usually the glassy form of which pale volcanic rock, whose stiff lava piles up into domes?

Rhyolite lava is extremely viscous, so atoms cannot shuffle into crystals before it chills, and a whole flow can set as natural glass.

Which compound, the main ingredient of ordinary window glass, makes up 70% or more of obsidian?

Silica makes lava thick and sticky, so its atoms struggle to line up into crystals before the flow freezes, which is why obsidian forms only from the most glass-prone lavas.

Which ancient Mexican city of the Pyramid of the Sun exported fine obsidian tools across Mesoamerica?

Teotihuacan had more than 100 obsidian workshops, and the trade has been seen as a key part of the city's rise to power.

Which variety name is given to obsidian patterned with radiating clusters of the mineral cristobalite?

Snowflake obsidian gets its look as the glass begins to crystallise, each pale blotch growing outward from a single point.

Since the 1970s, Technics and other makers have used slabs of obsidian as plinths for which audio equipment?

Turntables from Technics could sit on the SH-10B3, a greyish-black plinth cut from obsidian, one of the few modern uses of the rock that has nothing to do with its edge.

Mayor Island, whose other name Tūhua is also a local word for obsidian, lies off which country's coast?

New Zealand's Māori prized the island's black volcanic glass for cutting tools, while Captain Cook named the same island after London's Lord Mayor's Day.

Archaeologists can match an obsidian blade to the very volcano it came from by measuring what?

Its trace elements work like a fingerprint, because each volcano, and sometimes each eruption, produces glass with its own chemical signature.

A rare surviving Aztec obsidian-edged sword was destroyed in an 1884 fire at the Royal Armoury of which capital?

Madrid's fire destroyed what was long thought to be the last authentic example, though two damaged ones were later excavated in Mexico City.

Lipari, a Stone Age obsidian-trading hub, is the largest of the Aeolian Islands off which larger Italian island?

Sicily's small neighbour was shipping finely made obsidian bladelets as far as the Po valley and Croatia by the late Stone Age.

Nanoscale grains of which iron oxide mineral give most black obsidian its dark colour?

Magnetite also paints fire obsidian: thin layers of its nanoparticles split light into a shimmering rainbow through thin-film interference.

Which seafaring Pacific culture, ancestors of the Polynesians, traded obsidian over long distances around 1000 BC?

Lapita people made and stored their obsidian tools with such care that archaeologists think the glass carried prestige as well as a cutting edge.

Obsidian tools from Chaitén Volcano have been found 400 km away at prehistoric sites in which South American country?

Chile's Chaitén glass travelled about 400 km both north and south of the volcano, a measure of how far people would carry a good cutting stone.

Glass Mountain, a steep and nearly treeless obsidian flow, spilled from Medicine Lake Volcano in which US state?

California's Glass Mountain erupted only about 1,000 years ago, the most recent outburst of a huge shield volcano northeast of Mount Shasta.