50 Fun Facts About Granite

Which of these is the main type of rock that granite belongs to?

It crystallises slowly from silica-rich magma underground, which is why its individual grains are large enough to see.

The word "granite" comes from the Latin granum, meaning what?

The name refers to the coarse, completely crystalline texture that you can see with the naked eye.

Which of these minerals is NOT one of granite's main ingredients?

Calcite is the stuff of limestone and marble; granite is built from quartz, feldspars and mica or amphibole.

By modern convention, true granite contains what proportion of quartz by volume?

Rocks with more than 60% quartz are simply called quartz-rich granitoids, and those with almost nothing else are quartzolite.

What is the extrusive (volcanic) equivalent of granite?

Same chemistry, but erupted and cooled fast at the surface, so the crystals stay tiny.

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

The big crystals are called phenocrysts and are usually alkali feldspar.

What is the approximate density of granite?

That is roughly two and three-quarter times the density of water; its compressive strength usually exceeds 200 megapascals.

Roughly what is the melting temperature of dry granite at ambient pressure?

Add water at a few hundred megapascals of pressure and the melting point drops to about 650 °C.

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

The word comes from Greek for deep stone, and batholiths are built from many individual plutons.

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

The loose end product of fully weathered granite is called grus.

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

It is the second leading cause of lung cancer in the United States after smoking.

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

Gabbro has a completely different chemistry, but the construction trade uses 'granite' loosely for many intrusive rocks.

Which relief-carved granite obelisk deteriorated badly within 200 years of moving to damp, polluted London?

Its twin stands in New York's Central Park, where it has suffered similar weathering.

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

Aswan granite travelled hundreds of kilometres down the Nile to Giza around 2580 BC.

The world's first temple built entirely of granite was completed in 1010 AD in which country?

Rajaraja Chola I's Brihadeeswarar Temple at Tanjore carries a single 80-tonne granite block atop its tower.

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

Its granite sparkles like silver because of high mica content, and Rubislaw quarry supplied it for more than 300 years.

Aberdeen's Marischal College is the world's second-largest granite building after which one?

King Edward VII opened the Broad Street extension, designed by Alexander Marshall Mackenzie.

Which Scottish inventor's steam-powered cutting tools launched the polished granite tombstone trade in the 1830s?

His first polished Aberdeen granite headstone at Kensal Green Cemetery in 1832 caused a sensation in London.

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

The island is now a bird reserve, yet 60 to 70 percent of the world's curling stones still come from its rare granite.

America's first railroad, the 1826 Granite Railway, hauled Quincy stone to build which Charlestown landmark?

Solomon Willard chose the Quincy quarry after searching all New England, and Gridley Bryant designed the line.

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

Its Barre Gray stone is prized for outdoor sculpture, and Italian immigrant carvers brought an anarchist labour movement to town.

The world's largest "deep hole" granite quarry, the E. L. Smith Quarry, is run by which Vermont company?

Founded in 1885 in Graniteville, the firm now cuts Devonian Barre granite with diamond wire saws and water jets.

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

He called it the Shrine of Democracy and worked from 1927 until his death in 1941, when his son Lincoln took over.

How tall is each presidential head carved into Mount Rushmore?

Each figure was meant to be shown to the waist, but funding ran out in 1941 and only Washington has any detail below the chin.

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

The six head-like knobs on the ridge were linked to Black Elk's 1873 vision; earlier the peak was called Cougar Mountain.

South Dakota historian Doane Robinson originally wanted Mount Rushmore to depict which figures?

His list included Lewis and Clark, Sacagawea, Red Cloud, Buffalo Bill and Crazy Horse before Borglum insisted on presidents.

How many Confederate figures appear in the giant relief finished on Stone Mountain in 1972?

Jefferson Davis, Robert E. Lee and Stonewall Jackson ride their horses Blackjack, Traveller and Little Sorrel.

Roughly how far does Stone Mountain's rock body continue underground at its longest?

The dome rises 825 feet above its surroundings and stretches into neighbouring Gwinnett County.

Half Dome in Yosemite is technically made of which granitic rock?

It is the exposed remains of a magma chamber that crystallised thousands of feet underground before erosion cut it in half.

Who made the first ascent of Half Dome in 1875, drilling iron eye bolts into the smooth rock?

He had first tried smearing pine pitch on his feet for grip; today hikers use a pair of steel cables on the same face.

How tall is El Capitan's granite face from base to summit along its tallest line?

The Mariposa Battalion named it in 1851, loosely translating the Miwok name Tutokanula, meaning rock chief.

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

He took just under four hours on the Freerider route, and the feat became the Oscar-winning documentary Free Solo.

How long did Warren Harding's team spend on the first ascent of El Capitan's Nose in 1958?

They used siege tactics with fixed manila ropes over an 18-month project.

Roughly how long is the single intrusive body exposed as the High Sierra's granite peaks?

Most of the Sierra Nevada Batholith is still buried; only its top has been uncovered by uplift and erosion.

Pikes Peak in Colorado is built of a distinctive pink granite. What gives it the colour?

The granite crystallised roughly 1.05 billion years ago at least 20 miles below the surface.

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

The Portuguese named it in the 16th century after the conical clay moulds used to ship sugar.

The Cairngorms plateau in Scotland is the eroded top of what kind of geological body?

Its Gaelic name Am Monadh Ruadh, the red hills, comes from granite screes that glow red in evening sun.

Free-standing granite outcrops on the Cairngorm plateau, such as on Ben Avon, are called what?

They are masses of less-jointed granite that resisted underground weathering and were later exhumed.

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

The name means roughly crumbly rock, because differing thermal expansion of its minerals makes it weather into sand.

New Hampshire's Old Man of the Mountain granite profile collapsed in which year?

The five ledges on Cannon Mountain fell on 3 May; residents rejected the idea of a replica but it stays on licence plates.

Which two-letter classification divides granite by igneous or sedimentary source rock?

Chappell and White proposed it; I-types host porphyry copper deposits while S-types carry tin ores.

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

Pressure release lets the rock expand outward, sculpting the rounded domes seen in Yosemite.

A granite containing both muscovite and biotite micas is known as what kind of granite?

Also called binary granite, it is typically potassium-rich and usually an S-type or A-type.

A 2008 study of 39 full-size granite countertop slabs found radiation levels that were what?

Radon emissions were also below average outdoor US concentrations, though only a fraction of slab types have been tested.

Roughly what share of modern curling stones are made from Ailsa Craig granite?

The island is now a wildlife reserve, but Kays of Scotland still quarries it under licence; the best stones can cost US$1,500.

Which Roman-era granite quarry islands, besides Egypt and Turkey, supplied imperial builders?

Quarrying ceased around the third century AD, and from Late Antiquity old granite was reused as 'spolia'.

Why did medieval stoneworkers saw ancient granite columns into discs rather than carve them?

Granite also case-hardens with age, becoming tougher the longer it is exposed.

What density do granite magmas have, compared with 2.8 Mg/m3 for high-grade metamorphic rock?

That difference gives the magma tremendous buoyancy, so its ascent is inevitable once enough accumulates.

In which Australian city is black granite used for the paving and kerbs throughout the CBD?

Granite suits pavements because it is extremely durable, permeable and needs little maintenance.

The Trango Towers, a famous granite climbing venue, are in which mountain range?

Climbers prize granite for its steepness, soundness, crack systems and friction, from Yosemite to Patagonia's Fitzroy Massif.