Au on the Periodic Table: Gold Facts, Rarity, Output

Au is the chemical symbol for gold, element 79 on the periodic table. Gold is a dense, soft transition metal in group 11 and period 6, with a standard atomic weight of 196.96657 (PubChem periodic table). The symbol comes from the Latin word aurum, which is why it does not look like the English name. Below you will find the full fact sheet, how Au compares with its neighbours, how much gold exists, where it is mined and a calculator that turns any gold item into grams of pure Au.

Gold (Au) on the periodic table: key facts at a glance

Gold sits in the middle of the d-block, the block of transition metals. It is one of three “coinage metals” in group 11, together with copper and silver. Gold is also one of the noble metals, a group of metals that resist corrosion and oxidation. The table below gives the values that students, jewellers and miners look up most often.

Values come from the PubChem periodic table of the US National Library of Medicine, and the isotope and atomic-weight data from the US National Institute of Standards and Technology (NIST). The International Union of Pure and Applied Chemistry (IUPAC) is the body that maintains the official periodic table and its atomic weights.

What the numbers mean

The atomic number, 79, is the count of protons in every gold atom. The atomic weight, about 197, is the average mass of an atom measured on a scale where carbon-12 is exactly 12. Because natural gold has only one stable isotope, gold-197, the atomic weight is almost the same as the mass of that single isotope. A mole of gold, which is 6.022 x 10²³ atoms, therefore weighs about 197 grams.

The electron configuration explains much of gold’s behaviour. The outer 6s level holds a single electron and the 5d level below it is full. Gold keeps its electrons tightly, which is why it has a high ionization energy and an electronegativity of 2.54, high for a metal. In practical terms, gold reacts with very little. It does not rust, it does not tarnish in air, and it dissolves only in a few strong mixtures such as aqua regia, a blend of nitric and hydrochloric acid.

Why gold is Au: the Latin names behind the symbols

Many chemical symbols follow the Latin or older names of elements, not the English ones. Gold is Au from aurum, silver is Ag from argentum, copper is Cu from cuprum, iron is Fe from ferrum and lead is Pb from plumbum. This is why searchers ask “why is gold Au” and “is Au gold or silver”. The answer is simple: Au is gold, and Ag is silver.

A quick way to remember the pair is that Au sounds like “aurum”, the root of words such as “aureate” (golden). Ag, from “argentum”, is the root of “Argentina”, a country whose name means “land of silver”. If you see AU in capital letters it can also mean “astronomical unit” or the country code for Australia, but in a chemistry or mining context Au means gold.

Where gold sits in group 11: copper, silver and gold compared

Group 11 is a column of the periodic table, and its first three members are the metals people have used for coins and jewellery for thousands of years. The fourth, roentgenium (symbol Rg, number 111), is made in a laboratory and exists only for fractions of a second, so it has no practical use. The table compares the three natural members.

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Density of gold compared with other metals

Grams per cubic centimetre, rounded to one decimal

Each member of the group has one electron in its outer shell and a full d-level below it, which is why all three conduct electricity so well. Gold is the heaviest of the three and the least reactive. Copper and silver tarnish and corrode, while gold does not. Gold melts at a lower temperature than copper but higher than silver, which is one reason goldsmiths can alloy it with either metal at workshop temperatures.

Density is where gold stands out most among common metals. At 19.28 g/cm3 it is about 2.2 times as dense as copper and 1.8 times as dense as silver. Only a few metals, such as platinum, iridium and osmium, are denser. The chart below shows gold next to metals it is often compared with. Tungsten has almost the same density as gold; weight alone does not prove a bar is gold, so assay testing is used.

How rare is gold? Crust abundance and gold above ground

Gold is one of the rarest metals in the crust of the Earth. A US Geological Survey circular puts estimates of the average gold content of the crust at 0.001 to 0.006 parts per million, which is 1 to 6 parts per billion. A figure of about 4 parts per billion is often quoted inside that range.

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Where the world’s mined gold is held

Tonnes, end of second quarter, rounded by the source

Because such low averages cannot be mined, gold only becomes ore where natural processes have concentrated it. Hot, mineral-rich water can deposit gold in quartz veins and in sulphide minerals. Rivers can sort heavy gold grains into gravel beds called placers, from which panners and dredges recover them. Very old river deposits, called paleoplacers, are the source of the largest gold fields known.

The World Gold Council estimates that about 222,600 tonnes of gold had been mined in all of history by the end of the second quarter of its latest estimate, and that around two-thirds of that has been mined since 1950 (World Gold Council, above-ground stock, updated August 2026). Gold does not wear out, so almost all of it still exists as jewellery, bars, coins, central bank reserves or electronics. The Council notes that if all of it were melted into one cube, each side would be only about 22.6 metres.

The same page splits that stock by holder, as the chart below shows. Jewellery is the largest share, at roughly 45 percent, followed by bars and coins and then central banks. The US Geological Survey estimates world gold reserves at 66,000 tonnes (2026). Reserves are the part of a deposit that can be mined at a profit today, so they move with price and technology.

▶ Explains in clay how gold formed: from colliding stars to hot water and earthquakes. · 4:16

Which countries mine the most gold

Gold mining is spread across every continent except Antarctica. The US Geological Survey estimates world mine production at 3,300 tonnes for 2025, up slightly from 3,280 tonnes in 2024 (USGS Mineral Commodity Summaries 2026). China is first at an estimated 380 tonnes, about 12 percent of the world total. Russia follows at 310 tonnes and Australia at 280 tonnes. Canada produced an estimated 200 tonnes, the United States 160 tonnes, Ghana 150 tonnes and Mexico 140 tonnes. Kazakhstan and Uzbekistan each produced about 130 tonnes.

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Gold mine production by country, 2025 estimate

Tonnes of contained gold

The US figure is dominated by Nevada, which supplied about 64 percent of domestic output, followed by Alaska at about 22 percent (USGS, 2026). The Carlin Trend in Nevada, shown in the satellite image at the top of this page, is one of the best known gold belts in North America. For a state-by-state view, see our guide to how gold deposits are found.

Other organisations count slightly differently. The World Gold Council puts 2025 mine production at 3,672 tonnes, a record, based on a different set of company and industry data (Gold Demand Trends, full year 2025). Compare figures only when they come from the same publisher and year.

How gold is mined and extracted

Gold ore is rarely gold-coloured. In most mines, the gold is invisible grains in rock, and an ore may hold only a few grams per tonne. One gram per tonne is one part per million. A mine therefore moves a great deal of rock for a small amount of metal. Three broad methods cover most of the world’s gold.

Placer mining

Placer mining targets gold that water has already weathered out of its host rock and deposited in gravel. Small operators use pans and sluice boxes, which rely on gold being about 19 times as dense as water so that it sinks while lighter sand washes away. Larger operations use dredges and gravity circuits built on the same principle. Anyone panning for gold needs permission from the landowner or claim holder, and should never use mercury, which is toxic and illegal for this purpose in many places.

Hard-rock mining

Hard-rock, or lode, mining follows gold in veins and mineralised zones. It can be open pit near the surface or underground where the ore lies deep. Rock is drilled, blasted, hauled and crushed, then ground to powder so that the gold is exposed for recovery.

Leaching, gravity and flotation

Most gold is recovered from crushed ore with cyanide solution, in which gold dissolves and is then captured on activated carbon. Gravity circuits recover coarse gold, and flotation concentrates gold held in sulphide minerals before further treatment. Heap leaching stacks crushed ore on a lined pad and trickles solution through it, which suits low-grade ore. Operators must follow strict handling, storage and water rules around any cyanide use.

The video below follows a small clay nugget from the rock to the finished ring, step by step.

▶ Follows a small clay nugget through drilling, crushing, leaching, melting and refining. · 5:27

What gold is used for: jewellery, investment and technology

The World Gold Council counted total gold demand above 5,000 tonnes in 2025 for the first time, once over-the-counter trade is included (Gold Demand Trends, full year 2025). Investment demand was the largest sector at 2,175 tonnes, after exchange-traded fund holdings grew by 801 tonnes. Jewellery fabrication followed at 1,638 tonnes, central banks and other institutions bought 863 tonnes, and technology used 323 tonnes.

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Gold demand by sector, 2025

Tonnes

Technology is the small slice that matters most for the periodic table, because it depends on gold’s chemistry. Electronics took about 270 tonnes of that, and dentistry about 8 tonnes. Gold coats the contacts of connectors and circuit boards because it does not corrode, so a signal passes cleanly after years in a damp or hot setting. It also conducts heat and electricity, and it can be drawn into wire thinner than a human hair or beaten into thin leaf.

Space, medicine and industry

Thin gold coatings reflect infrared radiation, so spacecraft and satellites use gold-coated surfaces to manage heat. Medicine uses gold in some dental work.

Karat, fineness and what your jewellery contains

Pure gold is soft, so most jewellery is an alloy with copper, silver or other metals. Karat (K) measures gold in parts per 24. Twenty-four karat is nearly pure gold, 18K is 18 parts in 24 (75 percent gold), and 14K is 14 parts in 24 (58.3 percent). Many countries also stamp fineness in parts per thousand, so 750 means 75 percent gold. Alloys with more copper look redder, and alloys with silver or palladium look paler. The calculator further down turns a weight and karat into grams of pure Au.

Gold price history

The US Geological Survey tracks the annual average price in dollars per troy ounce: 1,801 in 2021, 1,802 in 2022, 1,945 in 2023, 2,388 in 2024 and an estimated 3,300 for 2025 (USGS Mineral Commodity Summaries 2026). The World Gold Council reports a 2025 annual average of US$3,431 per ounce on the LBMA PM price, which includes late-year rises, so published averages differ by method.

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Annual average gold price

US dollars per troy ounce (2025 is a USGS estimate)

Kitco showed spot gold at US$4,016.60 per troy ounce on 26 October 2026, 6:20 a.m. New York time, and listed an all-time high of US$5,589.38 reached on 28 January 2026 (Kitco gold price). Spot is the price for immediate delivery. Prices move every day, so check a live source before you make any calculation that matters.

A troy ounce is 31.1035 grams, not the 28.35 grams of an everyday ounce. Quotes for gold are almost always per troy ounce, so mixing the two units is the most common error when people value a piece of jewellery.

How much pure gold (Au) is in your item?

Use the calculator below with the weight and karat stamp of a ring, chain or bar. It returns grams of pure gold, troy ounces, the number of moles of Au atoms, and the melt value at the spot price you enter. The melt value is what the metal alone is worth. It is not what a dealer will pay, because dealers deduct refining costs and a margin, and jewellery sold at retail adds design and brand value.

Gold, exploration and traceable supply

Finding new gold is a separate problem from using it. Satellites cannot see gold itself. They map the rock around a deposit: iron-oxide staining, clay minerals, silica and faults, which are patterns that geologists link to gold systems. Those clues are exploration targets that need drilling and sampling before anyone can call them a resource. Farmonaut offers satellite mineral screening of licence areas, and the video below explains what such a map shows and what it does not. Our overview of mining cadastre portals shows how to check who holds the ground before you start.

The supply chain around gold also uses digital tools. Farmonaut’s product traceability system tracks goods from source to buyer, carbon footprinting estimates emissions from operations, and fleet management follows haul trucks and vehicles on mine sites. Site teams can also pull weather data from the satellite weather API when planning outdoor work.

▶ Explains that satellites cannot see gold itself but can map the alteration halo around gold systems. · 2:00

Frequently asked questions

What is Au on the periodic table?

Au is the symbol for gold, element number 79, a group 11 transition metal in period 6 with an atomic weight of about 197 (PubChem, NIST).

Why is gold Au and not Go or Gd?

The symbol comes from the Latin word aurum, meaning gold. Chemical symbols follow Latin or older names for several metals, including silver (Ag), iron (Fe) and lead (Pb). Gd is already taken by gadolinium.

Is Au gold or silver?

Au is gold. Silver is Ag, from the Latin argentum. Copper (Cu), silver (Ag) and gold (Au) share group 11 of the periodic table.

What is the atomic number of gold?

Gold has atomic number 79, which means every gold atom has 79 protons and, when neutral, 79 electrons.

How many isotopes does gold have?

Natural gold has one stable isotope, gold-197. Many other isotopes of gold exist but they are radioactive and short-lived (NIST).

Why is gold so rare?

The average crust holds only 1 to 6 parts per billion of gold (USGS Circular 603).

How much gold has been mined?

The World Gold Council estimates about 222,600 tonnes in total, roughly two-thirds of it since 1950 (Goldhub, August 2026 update).

Which country produces the most gold?

China, at an estimated 380 tonnes in 2025, ahead of Russia at 310 tonnes and Australia at 280 tonnes (USGS Mineral Commodity Summaries 2026).

Why doesn’t gold rust or tarnish?

Gold is a noble metal. Its electrons are held tightly, so it hardly reacts with oxygen or water, which is why ancient gold objects still shine.

What is the difference between 24K and 18K gold?

Twenty-four karat gold is nearly pure. Eighteen karat is 75 percent gold with 25 percent other metals, which makes it harder and better suited to everyday jewellery.

How do I find out the value of the gold in my jewellery?

Weigh the item in grams, read the karat or fineness stamp, convert to pure grams, divide by 31.1035 for troy ounces and multiply by the day’s spot price. The calculator on this page does these steps.