Quartz Trivia
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48 free Quartz trivia questions with answers — nature quiz, new questions added Oct 2026.
Quartz is the second most common mineral in the Earth's crust, the reference point for a 7 on the Mohs scale, and the reason your watch keeps time. This quiz starts with the mineral itself: silicon dioxide, the six-sided crystals, the alpha-beta flip at 573 degrees, why the Greeks called it krystallos and thought it was permanent ice, and Nicolas Steno's 60-degree angles that founded crystallography. The middle of the quiz is the coloured family. Amethyst and the drunkenness it was meant to prevent, citrine cooked from amethyst, rose quartz, smoky quartz and Scotland's Cairngorm, Bolivia's two-tone ametrine, banded agate and onyx, tiger's eye, red jasper, flint and the Stone Age. Then comes the technology: the Curie brothers discovering piezoelectricity in 1880, the first quartz clock at Bell Labs in 1927, the 32,768 Hz tuning fork inside almost every watch, and the Seiko Astron of Christmas 1969. It ends with the oddities: Herkimer diamonds, rhinestones from the Rhine, 19th-century crystal skulls sold as Aztec, shocked quartz from nuclear tests and impact craters, and a 40-tonne Brazilian crystal. Easy questions suit anyone who owns a quartz watch; the expert tier is for geology students and rockhounds. Every answer was checked against Wikipedia's articles on quartz, its varieties and its uses, and the supporting sentence is attached to each question.
30 of 48 questions with answers and explanations. Play the quiz
Q 01The sarsens, the huge blocks of which ancient monument, are a rock made almost entirely of quartz?
Stonehenge
Stonehenge. A core drilled from one sarsen during repairs in 1958 was kept as a souvenir for sixty years; once handed back, it showed grains of quartz cemented together by yet more quartz.
Q 02Quartz defines 7 on the Mohs scale; which gem mineral defines 8?
Topaz
Topaz. Friedrich Mohs picked ten minerals in 1812 so that each one scratches all those below it, so quartz will mark the six softer minerals on his list but is itself scratched by topaz.
Q 03Milky quartz owes its cloudy white colour to what trapped inside the crystal?
Tiny bubbles of fluid
Tiny bubbles of fluid. Milky quartz is very common, yet the gas and liquid sealed inside it as it grew leave it too cloudy to be wanted as a gemstone.
Q 04The Ancient Greeks called clear quartz krystallos because they believed it was a permanent form of what?
Ice
Ice. They took clear quartz for water frozen so deeply it would never thaw, and the idea is fossilised in our word 'crystal', from krystallos, which meant ice as well as the stone.
Q 05The word quartz is thought to come from an old Slavic word meaning what?
Hard
Hard, as in Czech tvrdý and Polish twardy. That is the favoured theory, though not the only one: a rival account traces the name to an old Saxon word for cross-vein ore.
Q 06The first practical use of quartz's piezoelectric effect, in the First World War, was a device built to detect what?
Submarines
Submarines. The French physicist Paul Langevin sandwiched thin quartz crystals between steel plates to send out pulses of ultrasound and listen for the echo.
Q 07Quartz abruptly changes its crystal structure and volume at 573 °C, a notorious hazard in which craft?
Pottery
Pottery. Clay is full of quartz grains, so ware heated or cooled too quickly through that point can crack as the grains suddenly swell or shrink, a fault potters call dunting.
Q 08A quartz crystal's prism has as many sides as which of these?
Honeycomb cell
Honeycomb cell: six. Most crystals show a point at one end only, because they grew outward from a rock wall; the rare ones that grew unattached are pointed at both ends.
Q 09Kitchen worktops sold as 'quartz' are slabs of crushed quartz bound together with what?
Resin
Resin. The slabs are roughly nine-tenths ground quartz and one-tenth polymer glue, pressed and cured in a factory, which is why the trade's own name for them is engineered stone.
Q 10Which brothers discovered the piezoelectric properties of quartz in 1880?
The Curies
The Curies. Pierre was 21 and working with his older brother Jacques, years before he met Marie, and a quartz instrument the brothers built went on to help her measure radioactivity.
Q 11The word piezoelectricity means electricity resulting from what?
Pressure
Pressure. Squeeze a quartz crystal and a voltage appears across it, and the trick runs backwards too: apply a voltage and the crystal flexes, the steady twitch that keeps a quartz watch on time.
Q 12The first quartz clock was built in 1927 by the engineer Warren Marrison at which laboratory?
Bell Telephone Laboratories
Bell Telephone Laboratories. Marrison was not trying to tell the time at all: he was after a steadier electrical frequency standard, and the clock fell out of counting a crystal's vibrations.
Q 13The quartz crystal in most watches, oscillating 32,768 times a second, is cut in the shape of a tiny what?
Tuning fork
Q 21Most commercially sold citrine, the yellow gem, is actually produced how?
Heating amethyst or smoky quartz
Heating amethyst or smoky quartz. Natural citrine is rare, so most of what the shops sell began as another colour of quartz and was baked until it turned yellow or orange.
Q 22The two-tone purple and yellow quartz called ametrine is mined almost entirely in which country?
Bolivia
Bolivia. Nearly all of it comes from one remote mine in the east of the country; legend has it a Spanish conquistador found the deposit in the 1600s, after which it lay forgotten for three centuries.
Q 23Heliotrope, a dark green quartz gemstone flecked with red, is better known by which name?
Bloodstone
Tuning fork. The odd-looking number is 2 to the power of 15, so a chip need only halve the count 15 times over to arrive at one tick a second.
Q 14The world's first commercial quartz wristwatch, the Astron of December 1969, was made by which company?
Seiko
Seiko. Quartz watches soon grew cheap and plentiful, and the flood of them dealt Switzerland's mechanical watchmakers the blow remembered as the quartz crisis.
Q 15Slices of quartz crystal were first widely used to stop which stations drifting off their frequencies?
Radio
Radio. In the 1920s stations wandered off their assigned frequencies and interfered with their neighbours; a slice of quartz, which keeps to one fixed rate, locked each transmitter in place.
Q 16The Second World War's demand for quartz crystals pushed industry to start doing what?
Growing them
Growing them. Mines could not keep up, so engineers learned to grow quartz from superheated, silica-rich water, much as nature does, and today most electronic quartz is made that way.
Q 17The Spruce Pine Mining District, a major source of ultra-pure quartz for silicon wafers, is in which US state?
North Carolina
North Carolina. This one Appalachian district is among the few places on Earth with quartz pure enough for chip-making, so when a hurricane flooded it in 2024 the mines stopped and chip-makers faced the threat of a shortage.
Q 18Quartz is one of the main minerals in which speckled rock, widely used for kerbstones, monuments and worktops?
Granite
Granite. Its glassy grey grains are quartz, and you can pick them out by eye because the molten rock cooled slowly deep underground, giving every crystal time to grow large.
Q 19Amethyst takes its name from Greek words meaning what?
Not intoxicated
Not intoxicated. The Greeks linked the wine-coloured stone with Dionysus and believed it kept a drinker sober; centuries later bishops took to wearing it in their rings.
Q 20Amethyst ranked with diamond and ruby as a 'cardinal gem' until huge deposits found in which country made it plentiful?
Brazil
Brazil. Until then fine amethyst came from only a few places, such as Russia's Urals; afterwards a gem once as rare as ruby became one almost anyone could afford.
Bloodstone. The red flecks owe their colour to haematite, a mineral whose own name comes from the Greek for blood, so the stone is named for blood twice over.
Q 24Smoky quartz gets its brown-to-black colour from what acting on it underground?
Natural radiation
Natural radiation. Rays from the surrounding rock work on traces of aluminium in the crystal, and clear quartz can be turned smoky the same way in a laboratory.
Q 25Cairngorm quartz, a smoky variety, is named after mountains in which country?
Scotland
Scotland. Nineteenth-century fashion for Highland jewellery soon outran what the mountains could supply, so many of the stones sold as cairngorms had never been near them.
Q 26Layered onyx, a pale band over a dark one, was the classic stone for which jewellery?
Cameos
Cameos. The carver cut the figure from the pale upper band and cleared the rest away to bare the dark band beneath, so that a pale figure stands out against a dark ground.
Q 27The microcrystalline forms of quartz, such as carnelian and onyx, are grouped together under what name?
Chalcedony
Chalcedony. Its crystals are so fine they show only under a microscope, and the stone is porous enough to drink up dye, which is how many of the vividly coloured slices in gift shops got their colour.
Q 28Ancient writers said which banded gem was named after the Achates, a river in Sicily?
Agate
Agate. Theophrastus and Pliny both told the story, though word historians point out that the river could just as easily have been named after the stone.
Q 29Onyx comes from the Greek for which body part, which its pink-and-white bands resemble?
Fingernail
Fingernail. The name was coined for pink-and-white banded stones, a long way from the solid black most people picture, and English 'nail' is a distant cousin of the same Greek word.
Q 30Chatoyancy, a gliding band of light on polished stone, marks which golden-brown quartz gem?
Tiger's eye
Tiger's eye. Fine parallel fibres run through the quartz, and light glancing off them makes the moving stripe, also called a cat's-eye.