50 Fun Facts About Crystal

The word crystal comes from the Ancient Greek krustallos, which meant both 'rock crystal' and what?

Greek philosophers including Theophrastus thought quartz was supercooled ice, an idea Pliny the Elder repeated and which lasted into the 17th century.

Despite the name, lead crystal and crystal glass are actually what kind of solid?

Glass has no periodic arrangement of atoms at all, unlike true crystals such as table salt or diamond.

Crystal structures are grouped into how many crystal systems?

Halite's cubes belong to the cubic system, while ordinary water ice is hexagonal.

Which symmetry can quasicrystals show that is impossible for an ordinary periodic crystal?

The holmium-magnesium-zinc quasicrystal can even grow as a pentagonal dodecahedron; the discovery forced crystallographers to redefine the word crystal.

Quartz defines which value on the Mohs hardness scale?

Its name comes from the German Quarz, ultimately from a Slavic word meaning 'hard'; it is a framework of silicon-oxygen tetrahedra with formula SiO2.

Whose 17th-century study of quartz paved the way for modern crystallography?

Roman naturalist Pliny had believed quartz was permanently frozen ice.

Amethyst gets its name from a Greek word meaning what?

Ancient Greeks carved drinking vessels from it believing it prevented drunkenness; the violet colour comes from irradiated iron impurities.

The Cave of the Crystals near Naica, Mexico, holds giant crystals of which mineral?

The largest is 11.4 metres long and weighs an estimated 12 tonnes; the chamber reaches 58°C with up to 99% humidity.

Who discovered the Cave of the Crystals in April 2000?

Juan and Pedro Sánchez broke into it while drilling; the crystals grew over at least 500,000 years and the cave reflooded by 2015.

Roughly how long did the Naica crystals take to grow to their enormous size?

Gypsum crystallised extremely slowly once the water cooled below about 56°C above a magma chamber.

A snowflake's six-fold symmetry comes from what?

Fewer than 0.1% of snowflakes are perfectly symmetrical, and rare twelve-branched flakes still keep the six-fold pattern.

Guinness lists the largest snowflakes, 15 inches wide, as falling in 1887 at Fort Keogh in which state?

Normal aggregated flakes top out at 3 or 4 inches.

Wilson 'Snowflake' Bentley photographed his first snowflake in 1885 on his family farm in which state?

He caught flakes on black velvet, attached a bellows camera to a microscope, and popularised the idea that no two snowflakes are alike.

Which physicist won the 1914 Nobel Prize for showing that crystals diffract X-rays?

The idea came up in a conversation in Munich's English Garden, and the first pattern was shot through a copper sulfate crystal.

Which father-and-son pair shared the 1915 Nobel Prize in Physics for their crystallography work?

The younger Bragg's law links X-ray scattering to evenly spaced planes of atoms; the first structure solved, in 1914, was table salt.

What was the first crystal structure solved to atomic resolution, in 1914?

Copper, fluorite, calcite and pyrite followed the same year, and spinel in 1915.

The United Nations proclaimed which year the International Year of Crystallography?

The proclamation came in July 2012, a century after von Laue's diffraction experiment.

Which French siblings discovered piezoelectricity in 1880 using crystals such as quartz and tourmaline?

Pierre and Jacques found quartz and Rochelle salt gave the strongest effect; it now sparks gas lighters and stoves.

At what frequency does the tuning-fork quartz crystal in nearly all quartz timepieces vibrate?

The first quartz clock was built by Warren Marrison at Bell Labs in 1927; Seiko's Caliber 35A of 1969 was the first quartz wristwatch movement.

Where was the first quartz clock built in 1927?

Warren Marrison's clock was accurate to 0.01 second per day; Junghans's Astrochron of 1967 was Europe's first consumer quartz clock.

Under EU rules, glass may only be labelled 'lead crystal' if it contains at least how much lead oxide?

The lead raises the refractive index, giving the sparkle, but it can leach into food and drink; lower-lead glass must be sold as 'crystal glass'.

Swarovski built its crystal-cutting factory in which Austrian town for hydroelectric power?

Founder Daniel Swarovski was born in Bohemia; the company adopted its edelweiss logo in 1899 and now also owns Swarovski Optik and Tyrolit.

Crystal-making in Waterford, Ireland dates back to 1783 and which pair of founders?

That original glassworks shut in 1851; the modern company's main plant closed in 2009 and the brand now belongs to Fiskars.

Which 1851 Joseph Paxton building for the Great Exhibition took its nickname from a Punch quip?

Its 293,000 panes of glass were made by Chance Brothers; rebuilt at Sydenham, it burned down in November 1936.

Rotary jeweller's tool marks on the British Museum's crystal skull date it to which century?

The skulls were most likely made in Idar-Oberstein, Germany, from Brazilian quartz, and many passed through Paris dealer Eugène Boban.

Which German town, famous for working Brazilian quartz, is the likely origin of the "ancient" crystal skulls?

The British Museum skull came via Tiffany & Co. in New York, and Paris's came from ethnographer Alphonse Pinart.

Which Elizabethan mathematician and consultant to Queen Elizabeth I is famous for scrying with crystals?

The tomb of the fifth-century Frankish king Childeric I even held a small transparent beryl globe.

What does scientific research say about crystal healing?

A 1999 study by French and Williams tested real crystals against fakes; the practice is considered pseudoscience.

Diamond crystallises in which crystal system?

Its typical habit is octahedral, and Antoine Lavoisier proved in 1772 that it was pure carbon by burning one under a lens.

Most natural diamonds are how old?

They reached the surface much later in volcanic eruptions, carried up in kimberlite and lamproite rocks.

The Cullinan, the largest gem-quality rough diamond ever found, weighed how many carats?

Found in South Africa in 1905, it was cut in Amsterdam by Joseph Asscher & Co.; Cullinan I sits in the Sovereign's Sceptre.

Herkimer 'diamonds', found in dolomite in New York's Mohawk Valley, are actually what?

The name honours their clarity and well-formed faces; they are also called Middleville or Little Falls diamonds.

Halite, or rock salt, forms crystals of which shape?

It has perfect cleavage in three directions and a Mohs hardness of only 2 to 2.5.

The rainbow colours on lab-grown bismuth 'hopper' crystals come from what?

The stair-step shape forms because the crystal edges grow faster than the faces.

Rock candy is made by letting a supersaturated sugar solution crystallise onto what?

Known as nabat in Iran, it grows bigger crystals when the water is heated before the sugar goes in.

Which Austrian botanist discovered liquid crystals in 1888 while studying cholesterol from carrots?

Otto Lehmann's 1904 book gave them the name, and RCA's Richard Williams found their electro-optic effects in 1962.

Large amethyst-lined geodes are a feature of the basalts of which two South American countries?

In the United States geodes are common in Indiana, Iowa, Missouri, western Illinois, Kentucky and Utah.

Roughly what share of snowflakes actually show the ideal six-fold symmetric shape?

Ukichiro Nakaya's morphology diagram links each crystal shape to the temperature and humidity it grew in.

Diamond's name derives from a Greek word meaning what?

Adamas combines 'not' with 'to tame or overpower'.

Above what temperature does ordinary alpha-quartz abruptly turn into beta-quartz?

Beta-quartz is unstable at room temperature, so all the quartz around you is the alpha form.

Which of the British crown jewels holds Cullinan I, the 530-carat Great Star of Africa?

Cullinan II, the Second Star of Africa at 317 carats, is set in the Imperial State Crown.

Which scientist argued in 1907 that X-rays were not electromagnetic radiation?

He went on to share a Nobel with his son for crystallography anyway.

As of 1999, the world's largest known natural crystal, 18 m long in Madagascar, is which mineral?

The Malakialina giant is 3.5 m across and weighs about 380,000 kg, roughly the mass of a fully loaded jumbo jet.

Which impurity turns a diamond crystal slightly blue?

Impurities matter enormously: the only difference between ruby and sapphire is which trace atoms sit inside a corundum crystal.

Who received the 2011 Nobel Prize in Chemistry for discovering quasicrystals?

Quasicrystals were first found in 1982 and remain rare: only about 100 solids form them, versus roughly 400,000 known periodic crystals.

Chocolate can crystallise into how many different forms, only one of which suits candy bars?

Tempering chocolate is really about coaxing cocoa butter into the one polymorph with the right snap and melting point.

Which industrial technique grows large single-crystal boules, notably silicon for chips?

The Bridgman technique is the other classic boule-growing method; hydrothermal synthesis and sublimation are gentler alternatives.

What are crystals with obvious, well-formed flat faces called?

Anhedral crystals lack such faces, usually because they are just one grain jammed inside a polycrystalline solid.

The angular Widmanstätten patterns seen in iron meteorites result from what?

Because they cooled so slowly, iron meteorites are often single crystals or a few crystals several metres in size.

Which optical property makes a double image appear when you look through a crystal such as calcite?

It comes from anisotropy: crystal properties such as conductivity and stiffness can differ by direction, which glass normally cannot manage.