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Native Element · Native metal — copper group · Copper Group

Gold

Au

The metal behind every gold rush — soft enough to flatten with a fingernail’s pressure, heavy enough to sink straight through river gravel, and the reason ‘fool’s gold’ needed a name.

Hardness2.5–3
Crystal systemCubic
LusterMetallic
Sp. gravity15.6–19.3
ClassNative Element
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Gold specimen

Native gold — a flattened, branching (dendritic) crystal cluster — Photo: Alchemist-hp (talk) www.pse-mendelejew.de · CC BY-SA 3.0 de

What is Gold?

Gold is a chemical element and a mineral at once — native gold is simply the metal gold, written Au, occurring in nature as a solid. It is the most malleable and ductile metal known: a single ounce can be beaten into a sheet covering a large room or drawn into miles of hair-fine wire.

In nature, gold turns up in two main disguises. Lode gold grows inside quartz veins laid down by hot water deep underground. Placer gold is what’s left when those veins erode — gold is so dense and so resistant to corrosion that it survives the trip downstream and settles out in riverbeds, which is why a simple pan still works.

Almost no natural gold is pure. Most carries a few percent silver (when silver dominates, the alloy is called electrum), which pales the color and lowers the weight. Gold crystals — octahedra, wires and branching ‘dendritic’ clusters — are real but rare; most gold is found as grains, flakes and the occasional famous nugget.

In one sentence: Gold is soft (a fingernail nearly dents it), astonishingly heavy (SG up to 19.3), and famously malleable — it flattens under a blow rather than shattering, which is the quickest way to separate it from fool’s gold.

Physical Properties

The full data table is in the panel alongside. Here’s what those numbers actually mean.

Weight. Nothing else you’ll commonly pick up is this dense. Pure gold sits at 19.3 g/cm³ — nearly twice as heavy as lead — and even silver-rich natural gold (15–19) outweighs pyrite or chalcopyrite (~5 and ~4) three or four times over. ‘Heft it’ is a real field test.

Malleability. Hit gold and it dents and flattens; hit pyrite and it shatters. This single test has sorted real gold from fool’s gold for centuries. Gold is also sectile — a knife shaves a curl off it rather than chipping it.

Color and streak. Gold’s streak is the same golden yellow as the metal — sulfide lookalikes streak greenish-black. Gold also never tarnishes: a nugget pulled from a tomb or a river looks the same after thousands of years.

Hardness. At 2.5–3 on the Mohs scale, gold is about as soft as a fingernail can mark — pure gold jewelry scratches and bends precisely because the metal is so soft.

How & Where It Forms

Most gold starts life dissolved — at parts-per-trillion levels — in hot, salty water moving through cracks deep in the crust. When that fluid cools or reacts with the wall rock, gold falls out of solution and grows with quartz in hydrothermal veins.

Weathering then does the prospector’s work. As veins erode, chemically inert gold survives while lighter minerals wash away, concentrating in stream beds as placer deposits — the flakes and nuggets of every gold rush. The largest gold source ever worked, South Africa’s Witwatersrand, is a fossil version of exactly this: gold-bearing river gravels turned to rock billions of years ago.

Often grows alongside:

QuartzPyriteChalcopyriteSilverGalenaArsenopyrite

What It’s Used For

Jewelry & wealthMost mined gold ends up as jewelry, bullion and coins — it doesn’t tarnish, so it keeps its shine for millennia.
ElectronicsThin gold coatings protect connectors and contacts: it conducts well and never corrodes.
Dentistry & medicineInert and biocompatible — used in crowns, implants and some injectable treatments.
Space & opticsGold film coats astronaut visors and satellite surfaces to reflect heat and radiation.

How to Identify It

Real gold is heavy, soft, and malleable — it flattens under a coin instead of shattering — and its streak is golden yellow, never black or greenish. Pyrite is hard, brittle and streaks greenish-black; chalcopyrite is brassier, brittle and also streaks dark; mica flakes are paper-light and springy. If it dents, weighs a lot and shines yellow forever, it’s gold.

Extremely heavy — pure gold is SG 19.3, and even alloyed natural gold dwarfs every lookalikeMalleable: flattens under a hammer or coin instead of shatteringGolden-yellow streak — the streak is the same color as the metalSoft (2.5–3): a copper coin scratches itNever tarnishes, rusts or corrodes
Looks like…But differs because…Quick test
Pyrite‘Fool’s gold’ is harder (6–6.5), brittle (shatters rather than flattens), much lighter (SG ~5) and leaves a greenish-black streakStreak + a tap
ChalcopyriteBrassier yellow, brittle, greenish-black streak, and often tarnishes iridescent; far lighter than goldStreak test
MicaGolden flakes in a stream pan are feather-light, flex and spring back, and never dentPinch and pan

Where It’s Found

Notable localities for fine specimens:

Witwatersrand Basin, South Africa Mother Lode, USA Klondike (Dawson City), Canada Ballarat, Australia Berezovsk, RussiaOpen the locality map →

References & Further Reading

  1. Dana’s New Mineralogy, 8th ed. Native elements — gold group.
  2. Mindat.org — Gold mineral data and locality records.
  3. Wikipedia — Gold.

Last reviewed 2026-09-14 · How to cite this page.