50 Fun Facts About Granite

Granite underlies much of the continents, but which rock underlies most of the ocean floor?

Basalt: it erupts as lava along the mid-ocean ridges, where new sea floor is made, and it is denser than the granite of the continents.

The word 'granite' shares its Latin root with the name of which fruit?

Pomegranate: its name means 'apple with many seeds', from the same Latin granum, 'grain', that named granite for its grainy look. Grenade belongs to the family too.

Which mineral, found in many granites as black or silvery specks, splits into paper-thin sheets?

Mica: granite's black flecks are often the mica biotite and its silvery ones muscovite, which is named after 'Muscovy glass', the clear sheets once used as window panes in Russia.

Which British Museum treasure is carved from granodiorite, a close cousin of granite?

The Rosetta Stone: French army engineers found the slab in 1799 while repairing a fort near Rashid in the Nile Delta, and its three scripts became the key to reading hieroglyphs.

What is the extrusive (volcanic) equivalent of granite?

Rhyolite: it is granite's magma erupted at the surface, where it chills too fast for big crystals to grow, so the same ingredients set as a fine-grained lava.

A granite with some crystals much larger than the groundmass has what texture?

Porphyritic: the outsized crystals are called phenocrysts. The word goes back to porphyry, the purple stone the Romans quarried in Egypt, which is speckled in just this way.

A block of granite sinks in water, but which liquid is dense enough for it to float on?

Mercury: granite is about 2.7 times as dense as water, but mercury is about 13.5 times as dense, so a granite block would ride on it with most of its bulk above the surface.

Deep in the crust, what can lower the melting point of granite by hundreds of degrees?

Water: dry granite melts at more than 1,200 °C, but water forced into the hot rock under pressure can bring that down to about 650 °C, cool enough for the deep crust to melt.

A large mass of plutonic rock exposed over more than 100 square kilometres is called what?

A batholith: the name was coined in the 1890s from the Greek for 'depth' and 'stone', which suits a body that froze miles down. The largest are welded together from many separate intrusions.

When feldspar in granite is chemically weathered by carbonic acid, which clay mineral does it turn into?

Kaolinite: the white china clay of fine porcelain, named after Gaoling, the Chinese hill where it was dug. Rain and soil water, faintly acid, slowly rot granite's feldspar into it.

Which radioactive gas, formed by the decay of uranium in granite, can collect in basements built over it?

Radon: it seeps up through cracks in floors and foundations, and the US Environmental Protection Agency ranks it second only to smoking as a cause of lung cancer.

The stone sold as "black granite" is usually which rock?

Gabbro: it is dark because it is rich in iron and magnesium minerals and has almost no quartz, yet once polished the stone trade sells it as 'black granite'.

Which name is shared by the ancient Egyptian granite obelisks that stand beside the Thames and in Central Park?

Cleopatra's Needle: both were raised at Heliopolis for Thutmose III about 3,500 years ago, well over a thousand years before Cleopatra was born.

The sarcophagus inside the Great Pyramid of Giza was carved from red granite quarried where?

Aswan: its quarries still hold an obelisk about 42 metres long, abandoned where it lay when cracks opened in the granite. Had it been raised, it would have been the tallest in Egypt.

The Brihadisvara Temple, a granite giant completed in 1010 by the Chola king Rajaraja I, stands in which country?

India: Rajaraja I raised it at Thanjavur in Tamil Nadu, and his builders set a single granite block of about 80 tonnes near the top of its thirteen-storey tower.

Which Scottish city, built largely from local grey stone, is nicknamed "The Granite City"?

Aberdeen: its Victorian streets were built of grey granite from Rubislaw quarry on the edge of town, a pit that closed in 1971 and is now a deep flooded hole among the houses.

Which vast royal monastery did Philip II build of grey granite near Madrid?

El Escorial: Philip II meant it as a royal tomb as well as a monastery and palace, and almost every Spanish monarch since his father, Charles V, lies buried in its crypt.

The granite blocks of which Thames bridge were sold to an American in 1968 and rebuilt in Arizona?

London Bridge: Robert McCulloch bought the 1831 bridge for his new desert town of Lake Havasu City, where its granite facing now wraps a concrete frame.

Curling stones are traditionally made from granite quarried on which Scottish island?

Ailsa Craig: one Scottish firm, Kays, has cut curling stones from its unusually tough granite for over 170 years, while the empty island itself has become a seabird sanctuary.

The Granite Railway of 1826, often called America's first commercial railroad, hauled Quincy stone for which landmark?

Bunker Hill Monument: the railway ran the granite from the Quincy quarries to a wharf on the Neponset River, and boats carried it on to Charlestown for the 221-foot obelisk, dedicated in 1843.

Which Vermont city calls itself the "Granite Center of the World"?

Barre: the Italian stonecutters its quarries drew made the town a stronghold of radical politics, with a Socialist Labor Party hall, built in 1900, that still stands and two Socialist mayors.

Which Washington memorial is a V-shaped wall of polished black granite carved with more than 58,000 names?

The Vietnam Veterans Memorial: Maya Lin, a 21-year-old architecture student, won the design contest, and the stone is polished like a mirror so that visitors see their own faces among the names.

Which sculptor carved the four presidents into the granite of Mount Rushmore?

Gutzon Borglum: he directed the blasting and carving from 1927 until he died in March 1941, and his son Lincoln saw the work through its last months.

About how tall is each presidential head carved into Mount Rushmore?

60 feet: and the plan was grander still, with all four presidents carved down to the waist, until the money ran out in October 1941.

What did the Lakota name for Mount Rushmore, Tȟuŋkášila Šákpe Pahá, mean?

Six Grandfathers Mountain: šákpe is six and tȟuŋkášila grandfather, a name tied to the six knobs along the ridge. An older Lakota name for the peak meant Cougar Mountain.

Doane Robinson, who dreamed up Mount Rushmore, first wanted the carving to show which figures?

Heroes of the American West: he had Red Cloud, Lewis and Clark and Buffalo Bill in mind, carved on the granite spires called the Needles, until the sculptor argued that presidents would give the work national appeal.

Which Confederate general rides alongside Jefferson Davis and Stonewall Jackson on Georgia's Stone Mountain?

Robert E. Lee: his face was begun in the 1920s by the man who went on to carve Mount Rushmore, but that work was blasted away and the present relief was finished only in 1972.

Which Inca citadel was built from granite quarried on its own mountain ridge, its finest walls fitted without mortar?

Machu Picchu: it was little known beyond its valley until 1911, when a local man, Melchor Arteaga, led the Yale scholar Hiram Bingham up to the ruins that Bingham then made world famous.

The colossal granite mountain carving begun in South Dakota's Black Hills in 1948 depicts which Lakota leader?

Crazy Horse: the Lakota elder Henry Standing Bear asked for the carving so the world would know that Native Americans have great heroes too. The face was finished in 1998, fifty years after work began.

In 1875 George Anderson became the first to climb which Yosemite landmark, once declared 'perfectly inaccessible'?

Half Dome: Anderson drilled his way up the smooth granite, standing on iron eye bolts as he went, and hikers now haul themselves up a pair of steel cables close to his line.

About how tall is the granite face of Yosemite's El Capitan from base to summit?

About 3,000 feet: the name is the Mariposa Battalion's 1851 Spanish rendering of a Miwok name that the battalion's doctor recorded as meaning 'rock chief'.

Which climber completed the first free solo ascent of El Capitan on 3 June 2017?

Alex Honnold: he went up the Freerider route alone, with no rope, in just under four hours, and the film of the climb, Free Solo, won the Oscar for best documentary.

Warren Harding's team took two seasons of siege climbing to make the 1958 first ascent of which El Capitan route?

The Nose: Harding finished it by hammering 28 bolts up the final overhang through the night, topping out at 6 a.m. on 12 November 1958.

Which California mountain range is the exposed top of a single mass of granite about 400 miles long?

The Sierra Nevada: most of that granite is still buried. Uplift and erosion have bared only its top, which now forms peaks such as Mount Whitney.

What gives the granite of Colorado's Pikes Peak its distinctive pink colour?

Potassium feldspar: the mineral, here the variety microcline, makes up much of the rock and is itself pink, helped by traces of iron. The granite is about a billion years old.

Rio de Janeiro's granite Sugarloaf Mountain belongs to which family of steep-sided outcrops?

Bornhardts: bald, steep-sided domes named after Wilhelm Bornhardt, the German geologist who first described them in East Africa. Sugarloaf's own name comes from the cone-shaped loaves refined sugar was once sold in.

Which range in the eastern Highlands of Scotland is the worn-down top of a great mass of granite?

The Cairngorms: their Gaelic name, Am Monadh Ruadh, means 'the red hills', for the granite screes that glow red in the evening sun. Mapmakers later renamed the range after one of its peaks.

Free-standing granite outcrops that crown hills such as those of Dartmoor are called what?

Tors: geologists still debate how they form, by frost or by groundwater rotting the granite while it lay buried, but either way a tor is the sound rock left standing once the weaker rock around it has gone.

The name of rapakivi granite, with its rimmed orthoclase crystals, comes from which language?

Finnish: rapakivi joins rapa, mud or grit, and kivi, stone, because the exposed rock crumbles so readily.

Which state's granite 'Old Man of the Mountain', lost in 2003, still appears on licence plates?

New Hampshire: for most of a century caretakers braced the cracking ledges with turnbuckles, steel rods and cables, but in May 2003 the face slid off Cannon Mountain all the same.

The granite beneath Cornwall and Devon is the source of which metal, mined there for some 4,000 years?

Tin: its ore, cassiterite, formed with the granite that surfaces at Bodmin Moor and Land's End, and copper, lead and tungsten have come out of the same ground.

What are the fractures called that make granite peel into onion-like sheets as overlying rock erodes?

Exfoliation joints: in the classic explanation, rock that formed under great pressure expands as its cover is stripped away and cracks in layers parallel to the surface, leaving rounded domes behind.

Which Indian Ocean island nation's main islands are granite fragments of the ancient supercontinent Gondwana?

Seychelles: Mahé and some forty neighbours are granite, a splinter left in mid-ocean when the supercontinent broke up, whereas most ocean islands are volcanic or coral.

The granite towers of Torres del Paine rise in which wild region at the southern end of South America?

Patagonia: the pale towers are tough granite, while the dark caps on neighbouring peaks are leftovers of the older rock the granite pushed into, all of it carved out by glaciers.

Which ancient Roman temple's porch stands on sixteen giant columns of granite shipped from Egypt?

The Pantheon: each column weighs about 60 tonnes. The grey ones were hauled more than 100 km across the desert from their quarry to the Nile, then shipped across the Mediterranean and up the Tiber.

Which California desert national park is famous for its piles of giant rounded granite boulders?

Joshua Tree: groundwater rounded the cracked granite into boulders while it was still buried, much as an ice cube under a tap loses its corners first, and floods later washed the soil away.

Builders in Late Antiquity lifted granite columns from older Roman monuments for new churches; what is such recycled stonework called?

Spolia: Latin for 'spoils'. Rome's granite quarries had closed by about the third century, so later builders took their columns ready-made from buildings that already stood.

Which pink-granite summit in Maine's Acadia National Park is the highest point on the US Atlantic coast?

Cadillac Mountain: its granite is about 420 million years old, and from early October to early March its summit catches the first sunrise in the United States.

Which Alpine range, famous for needle-like granite spires called aiguilles, straddles France, Italy and Switzerland?

The Mont Blanc massif: a Genevan scientist offered a prize for the first climb of its highest peak. A local doctor and his porter claimed it in 1786, a feat often counted as the birth of mountaineering.

The Trango Towers, granite spires near K2 in northern Pakistan, stand in which mountain range?

Karakoram: K2 itself is named for the range, as the second peak its first surveyors measured there, and the Trango Towers nearby have some of the tallest cliffs on Earth.