40 Fun Facts About Molybdenum

Molybdenum is named after the ancient Greek word for which metal, whose ores looked similar?

Lead, molybdos in Greek, lent its name because miners could not tell soft grey molybdenite from galena, the common ore of that heavier metal.

Which author made molybdenum's atomic number famous as a supercomputer's answer to everything?

Douglas Adams picked 42 for Deep Thought's answer in The Hitchhiker's Guide to the Galaxy purely as a joke. Every molybdenum atom happens to carry 42 protons.

Molybdenum-99 generators, 'milked' for a hospital isotope, are nicknamed after which animal?

Cow is the nickname, usually 'moly cow', because the decaying molybdenum keeps refilling the generator, which can be milked again about every six hours.

Molybdenum steel went into which giant German howitzer of World War I?

Big Bertha hurled shells of about a ton, and its makers chose molybdenum steel because the heat of the propellant was too much for ordinary gun steel.

A 14th-century sword from which country reportedly holds molybdenum, long before the metal was known?

Japan forged the blade around 1330. If its molybdenum was added on purpose, as reported, the practice never spread and was later lost.

Molybdenite, molybdenum's main ore, marks paper so well that it was long mistaken for which mineral?

Graphite and molybdenite look and feel so alike that telling them apart reliably takes laboratory equipment. The giveaway is that molybdenite is much denser.

Peasants at Knaben who found molybdenum ore first traded it pound for pound for which farm food?

Butter set the first known price of molybdenum ore, one pound for one pound. Once armies wanted the metal, the same weight of ore fetched three times as much.

Bacteria in the roots of clover and beans use a molybdenum enzyme to capture which gas from the air?

Nitrogen is turned into ammonia by nitrogenase, an enzyme with a molybdenum atom at its working centre. Without the metal, far less of the gas would ever reach living things.

X-ray tubes with molybdenum targets are the classic choice in machines screening for which disease?

Breast cancer screening relies on them because molybdenum gives off low-energy X-rays of about 17 to 20 keV, which show fine detail in soft tissue at a low dose.

Which US state has the Climax mine, which once supplied three quarters of the world's molybdenum?

Colorado's Climax mine sits about 11,360 feet up on Fremont Pass, on a deposit a prospector claimed in 1879 without knowing what the grey mineral was.

Which symbol stands for molybdenum on the periodic table, where it sits directly beneath chromium?

Mo is the symbol for molybdenum in group 6. Mn belongs to manganese and Md to mendelevium, while Mb is not an element at all.

In both world wars, molybdenum stood in for which scarcer metal used to harden tool steel?

Tungsten ran short in both wars, so steelmakers swapped in molybdenum. The M in high-speed steel grades such as M2 still marks the substitute.

Much molybdenum is a byproduct of mining which metal, as at Chile's vast Chuquicamata pit?

Copper and molybdenum occur together in huge low-grade deposits, so pits such as Bingham Canyon in Utah sell molybdenum as a valuable sideline.

Which country has long mined more molybdenum than any other and also holds the largest reserves?

China mined over 40 percent of the world's molybdenum in 2024, well ahead of South America and North America, the other two great producing regions.

Molybdenum-99 decays into which element, the workhorse of hospital nuclear medicine scans?

Technetium made this way is used in tens of millions of scans a year, more than any other medical radioisotope. It fades within hours, so hospitals must make it fresh.

Molybdenum in type 316 stainless steel, used on boats, stops pitting by which everyday substance?

Salt in seawater pits ordinary stainless steel, so the version with 2 to 3 percent molybdenum became known as marine grade. Surgical steel comes from the same family.

Which legume, a New Year's good-luck dish in the US South, tops tables of molybdenum-rich foods?

Black-eyed peas pack about 288 micrograms of molybdenum into half a cup, more than six times an adult's daily need.

Which Swedish chemist, an unlucky co-discoverer of oxygen, first identified molybdenum in 1778?

Carl Wilhelm Scheele showed that the mineral molybdena hid an unknown element but never isolated the metal himself. Another Swede, Peter Jacob Hjelm, did that three years later.

A 1976 Soviet probe brought back rock holding a microscopic grain of molybdenum from which world?

The Moon sample came from Mare Crisium, the Sea of Crises, where Luna 24 drilled about two metres down. The molybdenum grain was roughly a thousandth of a millimetre long.

Slippery molybdenum disulfide turns up in greases, bullet coatings and which winter-sport product?

Ski wax can carry molybdenum disulfide because the compound's layers slide over one another, the same trick that keeps bearings moving when oil is lost.

People very short of molybdenum react badly to which preservatives, common in wine and dried fruit?

Sulfites are normally made harmless by sulfite oxidase, one of only four human enzymes that need molybdenum. Without the metal the enzyme stalls and the preservatives build up.

In a part of Armenia with molybdenum-rich soil, heavy intake brought symptoms of which joint disease?

Gout-like aches appeared because a molybdenum enzyme, xanthine oxidase, makes uric acid, and the villagers' blood carried abnormally high levels of it.

A lack of molybdenum in soil causes whiptail, a disorder seen above all in which vegetable crop?

Cauliflower is the classic victim, and the cure is simple: growers add lime to acid soil, which frees the molybdenum that was locked up in it.

Wulfenite, a molybdenum mineral prized for orange-red crystals, is which US state's official mineral?

Arizona adopted wulfenite in 2017, and its Red Cloud Mine is one of the most noted sources of the thin, tabular crystals.

In which occupied country did Allied bombers twice raid the Knaben molybdenum mines during 1943?

Norway's Knaben mines were among the few in Europe still producing molybdenum, so British Mosquitoes struck in March and 130 American B-17s followed in November.

The first artificially made element was found in molybdenum foil taken from which kind of machine?

Cyclotron inventor Ernest Lawrence posted the radioactive scrap from California to Sicily, where Emilio Segrè and Carlo Perrier proved in 1937 that it held element 43.

Which country's Chalk River reactor was long the world's biggest source of medical molybdenum-99?

Canada's NRU reactor made more medical isotopes than any other facility, so when it was shut down in late 2007 hospitals around the world ran short.

Molybdenum belongs to which small family of elements, defined by great resistance to heat and wear?

Refractory metals number just five by the strictest count, and molybdenum is the most widely used of them, melting only at 2,623 °C.

Most medical molybdenum-99 is made in reactors by splitting atoms of which heavy element?

Uranium-235 targets are bombarded with neutrons, and about six percent of the atoms that split leave molybdenum-99 behind. It loses half its strength every 66 hours.

Chromoly, a molybdenum steel loved by bike frame builders, is classic tubing for which race-car part?

Roll cage builders prize chromoly for its strength-to-weight ratio, and the same family of alloys is accepted for the barrels of the US military's M16 rifle.

Tetrathiomolybdate, a molybdenum drug, was developed for which disorder named after a British neurologist?

Wilson's disease lets a toxic metal pile up in the body, and the bright red molybdenum compound binds it so that it can be flushed out. Vets used the drug on animals first.

Theonella conica, noted for hoarding huge amounts of molybdenum, is which kind of sea creature?

Sponge it is: Theonella conica is a hyperaccumulator, gathering molybdenum from seawater that holds only about 10 parts per billion of the element.

Chemists measure phosphate in water with a test named after molybdenum and which colour it turns?

Blue deepens in step with the phosphate present, so a simple colour meter can read off the amount, even in seawater.

Thin molybdenum wires long held up the white-hot coil inside which everyday electrical product?

Light bulbs gave molybdenum one of its first real markets once a 1906 patent showed how to make the brittle metal workable. The wire must be sealed away from air or it burns.

Peter Jacob Hjelm first isolated molybdenum metal by heating its oxide with carbon and which oil?

Linseed oil and carbon stripped the oxygen away in the heat, leaving a dark metal powder that Hjelm named after the mineral it came from.

Pairs of molybdenum atoms in a gas share which kind of bond, known in just one other element?

Sextuple bonds join the two atoms with six shared pairs of electrons, and the molecule exists only as a gas, made by blasting chilled molybdenum with a laser.

The human body stores molybdenum in the kidneys, adrenal glands, bone and which large organ?

Liver holds some of the body's highest concentrations of molybdenum, and beef liver is among the richest sources of the mineral in the diet.

Which General Electric scientist, later famed for his X-ray tube, patented ductile molybdenum in 1906?

William Coolidge found how to make the brittle metal bend and draw into wire, which opened its first uses as a heating element in high-temperature furnaces.

Which rare metal, used in jet engine blades, is recovered from the fumes of roasting molybdenum ore?

Rhenium makes up only about one part per billion of Earth's crust, so producers leach it from the flue dust of molybdenum roasters.

C. Harold Wills, whose Gray Goose car pioneered molybdenum steel, had been an aide to which carmaker?

Henry Ford's former aide had already put vanadium steel into the Model T, then insisted on molybdenum for every stressed part of his own Wills Sainte Claire cars.