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49 free Crystal trivia questions with answers — science & nature quiz, new questions added Aug 2026.
This crystal trivia quiz covers crystals in every sense of the word: the science (what makes a solid a crystal, the seven crystal systems, quasicrystals, X-ray crystallography and the Nobel Prizes it won), the minerals (quartz and amethyst, halite, bismuth, diamonds, geodes and Herkimer 'diamonds'), the natural wonders (Mexico's Cave of the Crystals, snowflakes and the man who first photographed them) and the crystals people make and sell, from Swarovski and Waterford lead crystal to rock candy and the quartz oscillators inside your watch. It also takes in the folklore and the fakes: crystal balls and John Dee, crystal healing and what the studies found, and the crystal skulls that turned out to be 19th-century German work. Difficulty runs from easy questions anyone with a rock collection can answer to expert ones about crystallography and history. Every answer was checked against a reference page before publishing, so the dates, names and numbers hold up.
30 of 49 questions with answers and explanations. Play the quiz
Q 01The word crystal comes from the Ancient Greek krustallos, which meant both 'rock crystal' and what?
Ice
Greek philosophers including Theophrastus thought quartz was supercooled ice, an idea Pliny the Elder repeated and which lasted into the 17th century.
Q 02Despite the name, lead crystal and crystal glass are actually what kind of solid?
Amorphous solids
Lead crystal and crystal glass are amorphous solids: their atoms have no long-range periodic order, so 'crystal' glassware is named for its sparkle and clarity, not its structure.
Q 03Crystal structures are grouped into how many crystal systems?
Seven
Crystallographers recognise seven crystal systems, defined by the symmetry of the unit cell; the 14 Bravais lattices and 32 point groups sort into them.
Q 04Which symmetry can quasicrystals show that is impossible for an ordinary periodic crystal?
Five-fold
Quasicrystals show five-fold (and ten-fold) rotational symmetry, forbidden for periodic lattices; a holmium-magnesium-zinc quasicrystal even grows as a pentagonal dodecahedron, and the IUCr redefined 'crystal' in 1992.
Q 05Quartz defines which value on the Mohs hardness scale?
7
Quartz is the reference mineral for 7 on the Mohs scale, between orthoclase feldspar at 6 and topaz at 8; it scratches ordinary window glass and a steel knife blade.
Q 06Whose 17th-century study of quartz paved the way for modern crystallography?
Nicolas Steno
Nicolas Steno showed in 1669 that quartz crystals keep the same angles between corresponding faces whatever their size or shape, the law of constant interfacial angles.
Q 07Amethyst gets its name from a Greek word meaning what?
Not intoxicated
Ancient Greeks carved drinking vessels from it believing it prevented drunkenness; the violet colour comes from irradiated iron impurities.
Q 08The Cave of the Crystals near Naica, Mexico, holds giant crystals of which mineral?
Selenite gypsum
The Naica crystals are selenite gypsum, the transparent crystalline form of the mineral; the largest is about 11.4 metres long, and the chamber sits at 58°C with humidity near 99%.
Q 09Who discovered the Cave of the Crystals in April 2000?
Two brothers drilling in the mine
Two brothers drilling in the mine, Juan and Pedro Sánchez, broke into the chamber in April 2000 while cutting a new tunnel at Naica; when the mine's pumps were later switched off the chamber reflooded.
Q 10Roughly how long did the Naica crystals take to grow to their enormous size?
At least 500,000 years
Fluid-inclusion studies indicate growth took at least 500,000 years, as mineral-rich water held just below 58°C let gypsum crystallise at an extremely slow rate.
Q 11A snowflake's six-fold symmetry comes from what?
The hexagonal crystal structure of ice
The hexagonal crystal structure of ice (ice Ih) sets the 60-degree angles between a snow crystal's arms; rare twelve-branched flakes are two such crystals grown together.
Q 12Guinness lists the largest snowflakes, 15 inches wide, as falling in 1887 at Fort Keogh in which state?
Montana
Fort Keogh, near Miles City in Montana, reported flakes 15 inches wide and 8 inches thick on 28 January 1887; typical aggregate flakes are no more than 3 or 4 inches across.
Q 13Wilson 'Snowflake' Bentley photographed his first snowflake in 1885 on his family farm in which state?
Vermont
Q 21Under EU rules, glass may only be labelled 'lead crystal' if it contains at least how much lead oxide?
24%
EU Directive 69/493/EEC reserves 'lead crystal' for glass with at least 24% lead oxide and 'full lead crystal' for 30% or more; lighter mixes are sold as 'crystal glass' or 'crystallin'.
Q 22Swarovski built its crystal-cutting factory in which Austrian town for hydroelectric power?
Wattens
Daniel Swarovski, a Bohemian-born glass cutter, set up in Wattens in the Tyrol in 1895 because local hydroelectric power could drive his patented electric cutting machine; the Kristallwelten museum opened there in 1995.
Q 23Crystal-making in Waterford, Ireland dates back to 1783 and which pair of founders?
George and William Penrose
Bentley, a farmer in Jericho, Vermont, caught flakes on black velvet and coupled a bellows camera to a microscope; his 1885 photomicrograph is considered the first of a single snow crystal.
Q 14Which physicist won the 1914 Nobel Prize for showing that crystals diffract X-rays?
Max von Laue
Max von Laue conceived the experiment in 1912 after a conversation with Paul Ewald in Munich; Friedrich and Knipping shot the first diffraction pattern through a copper sulfate crystal.
Q 15Which father-and-son pair shared the 1915 Nobel Prize in Physics for their crystallography work?
The Braggs
The father-and-son Braggs shared the 1915 prize; the son's Bragg's law relates X-ray wavelength and angle to the spacing of atomic planes, and at 25 he became the youngest physics laureate.
Q 16What was the first crystal structure solved to atomic resolution, in 1914?
Table salt
Table salt (sodium chloride) was the first structure solved by X-ray diffraction, a lattice of alternating sodium and chloride ions with no discrete molecules; copper, fluorite, calcite and pyrite followed.
Q 17The United Nations proclaimed which year the International Year of Crystallography?
2014
The UN General Assembly designated 2014 the International Year of Crystallography in July 2012, marking a century since the 1912 discovery that crystals diffract X-rays.
Q 18Which French siblings discovered piezoelectricity in 1880 using crystals such as quartz and tourmaline?
The Curies
The Curies, brothers Pierre and Jacques, found in 1880 that pressing quartz, tourmaline or Rochelle salt produced a voltage; Rochelle salt gave the strongest effect, and piezoelectric igniters spark gas lighters.
Q 19At what frequency does the tuning-fork quartz crystal in nearly all quartz timepieces vibrate?
32,768 Hz
The crystal vibrates at 32,768 Hz, which is 2 to the 15th power, so a chain of 15 binary dividers yields exactly one pulse per second; Seiko's Astron of 1969 was the first quartz wristwatch.
Q 20Where was the first quartz clock built in 1927?
Bell Labs
Warren Marrison and J. W. Horton built the first quartz clock at Bell Labs (Bell Telephone Laboratories) in 1927, using a crystal oscillator as a frequency standard for the telephone network.
That original glassworks shut in 1851; the modern company's main plant closed in 2009 and the brand now belongs to Fiskars.
Q 24Which magazine's quip gave Joseph Paxton's 1851 Great Exhibition hall the nickname Crystal Palace?
Punch
Punch's Douglas Jerrold called Paxton's glass hall 'a palace of very crystal', and the nickname Crystal Palace stuck; the building moved to Sydenham in 1854 and burned down in November 1936.
Q 25Rotary jeweller's tool marks on the British Museum's crystal skull date it to which century?
The 19th
Electron microscopy of the British Museum skull found grooves cut with a rotary wheel, a tool unknown in pre-Columbian Mesoamerica, so it was carved in the 19th century; it came via Paris dealer Eugène Boban.
Q 26Which Elizabethan mathematician and consultant to Queen Elizabeth I is famous for scrying with crystals?
John Dee
John Dee, Elizabeth I's astrologer and mathematician, used a crystal ball and an obsidian mirror with his medium Edward Kelley to 'converse with angels'; both objects ended up in the British Museum.
Q 27What does scientific research say about crystal healing?
Its effects match a placebo
Christopher French's experiments with real and fake quartz found the same reported sensations whichever crystals volunteers held, so its effects match a placebo; crystal healing is classed as pseudoscience.
Q 28Diamond crystallises in which crystal system?
Cubic
Diamond belongs to the cubic system: each carbon atom bonds tetrahedrally to four others in a face-centred cubic lattice, and its crystals typically grow as octahedra.
Q 29Most natural diamonds are how old?
1 to 3.5 billion years
Most natural diamonds formed 1 to 3.5 billion years ago at depths of 150 to 250 kilometres, reaching the surface much later in kimberlite and lamproite eruptions.
Q 30The Cullinan, the largest gem-quality rough diamond ever found, weighed how many carats?
3,106
The Cullinan, 3,106 carats (about 621 grams), was found at the Premier Mine near Pretoria in January 1905 and cut in Amsterdam by Joseph Asscher & Co. into nine major stones.