40 Fun Facts About Chromium

Traces of chromium turn clear crystals of aluminum oxide into which precious gemstone?

Ruby owes its red to chromium atoms that take the place of about one in a hundred aluminum atoms. The same crystal without chromium is called sapphire.

Trace amounts of chromium give which gemstone, a variety of the mineral beryl, its famous green?

Emerald is beryl tinted by chromium or sometimes vanadium, so the metal that makes one famous gem red makes another green.

Chrome yellow, a chromium pigment, was chosen in 1939 as the paint for which North American vehicles?

School buses wore a shade first officially named National School Bus Chrome. Its lead chromate pigment was later replaced because it is toxic.

Which 2000 film stars Julia Roberts exposing chromium-poisoned groundwater in Hinkley, California?

Erin Brockovich tells the true story of a case settled for $333 million in 1996, and it won Julia Roberts the Academy Award for Best Actress.

Chromium on 2,200-year-old bronze weapons at which Chinese site was long mistaken for an ancient protective coating?

Terracotta Army weapons were thought to have been chromium-coated to stop decay, until research in 2019 showed the metal was contamination from nearby lacquer.

Theodore Maiman used chromium atoms in a synthetic crystal to build the world's first working what?

Laser light first shone on May 16, 1960, at Hughes Research Laboratories, where the chromium in Maiman's crystal gave off a deep red beam.

Iron alloys with at least 10.5 percent chromium go by which name, familiar from sinks and cutlery?

Stainless steel is protected by an invisible film of chromium oxide that forms on its surface and can heal itself.

Chromium salts are used in making roughly 85 to 90 percent of the world's supply of which material?

Leather is mostly chrome-tanned, with chromium locking the collagen fibers of a hide together. Tanners borrowed the idea after 1840 from the treatment of surgical gut stitches.

Chromium is also the name of an open-source web browser project led by which technology company?

Google leads the Chromium project, whose code underpins not only Chrome but also Microsoft Edge, Opera and Samsung's browser.

Chromium takes its name from a word meaning color in which ancient language?

Greek chroma, meaning color, was chosen because chromium compounds range from red and orange to yellow, green and violet.

Chromium compounds come in vivid reds and greens, but what does the pure metal look like?

Steely gray, hard and brittle, chromium takes a high polish that reflects almost 70 percent of visible light.

Chromium belongs to which family of elements, found in the middle block of the periodic table?

Transition metals fill groups 3 to 12 of the table, and chromium is the first member of group 6.

Which Art Deco skyscraper in New York, completed in 1930, wears a crown of chromium-rich Nirosta steel?

Chrysler Building cladding was the first American use of the German alloy, which is 18 percent chromium and also covers the needle and window frames.

Nichrome, the wire that glows inside toasters, is an alloy of chromium and which other metal?

Nickel makes up about 80 percent of classic nichrome, which Albert Marsh patented in 1906 and which is the oldest documented alloy for electric heating.

Vincent van Gogh used chrome yellow, a chromium pigment that slowly browns, in which series of paintings?

Sunflowers studies show he mixed several shades of chrome yellow, a lead chromate pigment first made in the early 1800s.

Which country, home to the Bushveld Complex, has long been the world's largest producer of chromium ore?

South Africa has layers in its Bushveld Igneous Complex that are up to 90 percent chromite, the mineral mined for chromium.

Chromium dioxide, a magnetic compound, gave its name to premium 'chrome' versions of which music format?

Cassettes coated with chromium dioxide outperformed ordinary iron oxide tape. DuPont, which invented the manufacturing process, began selling the coating in 1968.

The mirror-bright chromium finish on car trim and taps is usually applied by which process?

Electroplating lays down a decorative chromium coat less than a thousandth of a millimeter thick. The process took off after an improved method arrived in 1924.

Chromium is the third-hardest element; only boron and which other element, in one crystal form, are harder?

Carbon in the form of diamond tops the list. Chromium rates 8.5 on the Mohs scale, hard enough to scratch quartz and topaz.

Chromium supplements are sold for a suspected, though unproven, role in helping which hormone do its job?

Insulin controls how the body stores sugar, fat and protein, but European regulators concluded in 2014 that chromium has not been shown to be an essential nutrient.

Crocoite, the orange-red mineral in which chromium was found, is the emblem of which Australian state?

Tasmania's old mines at Dundas have produced exceptional crocoite crystals, a lead chromate once ground up as a yellow paint pigment.

Harry Brearley created rustless chromium steel in 1913 while seeking better gun barrels in which English city?

Sheffield was already famous for cutlery, and a local cutlery maker who tried Brearley's alloy gave it the name that stuck.

Chromium heads group 6 of the periodic table, which also includes which metal with the chemical symbol W?

Tungsten sits two rows below chromium and has the highest melting point of any metal, 3,422 degrees Celsius.

Chromite deposits near which American port city made the United States the top chromium supplier until 1848?

Baltimore businessman Isaac Tyson, who first mined the ore on his own farm, came to hold a virtual monopoly on the world's chromium minerals.

Chromoly steel, prized for bicycle frames and roll cages, blends chromium with which other element?

Molybdenum and chromium are the alloying elements of the 41xx family of steels, which also go into gas cylinders, firearm parts and flywheels.

Armies paint vehicles with a chromium oxide pigment because it reflects infrared light much like what?

Green leaves and chromium oxide reflect infrared in the same way, so the paint keeps a camouflaged vehicle matched to the plants around it.

Chromium gives which gem its shift from green in daylight to red by lamplight?

Alexandrite honors the future Emperor Alexander II. Its chromium absorbs yellow light so strongly that the stone follows whichever of green or red its lighting favors.

Traces of chromium give 'imperial' stones, the most valuable variety of which gem, their intense green?

Jade of the imperial kind is jadeite with a little chromium in its crystals, while extra iron instead turns the stone a much darker green.

The chromium-based Phillips catalyst is used to make about half the world's supply of which plastic?

Polyethylene is the most-produced synthetic polymer of all, and a catalyst of chromium oxide on silica gel turns out roughly half of it.

CCA, a preservative that tints outdoor timber green, combines chromium with a second metal and which poison?

Arsenic is the reason American regulators and the lumber industry agreed in 2003 to stop using CCA-treated wood for decks, fences and playground equipment.

Which French chemist first isolated chromium by heating its oxide in a charcoal oven?

Louis Vauquelin also discovered the element beryllium, and he traced the red and green of two famous gemstones to chromium.

Chromium is the first element to break the usual order of electron filling; which fourth-row metal also does?

Copper also takes an electron from its outer 4s shell, in its case to complete the 3d shell, while chromium does it to leave both shells exactly half full.

Uvarovite, a chromium gemstone named after a Russian count, is the only consistently green member of which gem family?

Garnet is usually pictured as deep red, but chromium makes uvarovite bright green. It is also the rarest of the common members of the group.

The 1971 Byrd Amendment let the United States import chromium ore from which African state despite UN sanctions?

Rhodesia had supplied about 40 percent of American chrome before the boycott, and the Soviet Union supplied another 40 percent.

Doctors use radioactive chromium-51 as a tag to measure the volume and survival time of which part of the body?

Red blood cells are labeled with chromium-51, whose gamma rays and half-life of about 28 days let doctors follow them. It also helps diagnose internal bleeding.

The Kemi mine, where an amateur diver first spotted signs of chromium ore in 1959, lies in which Nordic country?

Finland's largest underground mine grew from that find, and its ore now feeds a ferrochrome plant at nearby Tornio.

Which blue-green pigment is a hydrated chromium oxide first made in Paris?

Viridian, named from the Latin for green, was first prepared in 1838 by the Parisian color chemist Pannetier, and a cheaper process patented in 1859 made it widely available to painters.

Chromium is the only solid element to show which magnetic ordering at room temperature?

Antiferromagnetism means neighboring atoms' magnetic moments point in opposite directions and cancel out. Chromium loses the ordering above 38 degrees Celsius.

Which American car pioneer co-discovered rustless chromium steel around 1912 and invented the hard alloy Stellite?

Elwood Haynes first devised Stellite as a material for cutlery that would not stain, and he designed one of the earliest American automobiles.

Which German arms maker, using chromium steel for cannons in the 1850s, later developed rustless Nirosta steel?

Krupp's name for the alloy is short for the German for non-rusting steel, and in 1908 a Krupp shipyard built the yacht Germania with a hull of chromium alloy steel.