Placer deposit

Ore deposit

Heavy minerals that resist weathering are washed out of their source rock and sorted by running water, waves or wind, and settle where the current slows: in river gravels, on beaches, in old buried river beds. A placer mineral must be heavier than quartz; black sands of magnetite and ilmenite mark them.

Where

River / Stream; Sandy Shore

Rocks

Nephrite

Minerals

Gold, Platinum, Cassiterite, Diamond, Garnet, Magnetite, Ilmenite, Hematite, Rutile, Zircon, Chromite, Wolframite, Ruby, Sapphire, Carnelian, Alexandrite, Painite, Bloodstone, Taaffeite, Kyawthuite, Poudretteite, Paraíba Tourmaline, Moss Agate, Sperrylite, Cooperite, Osmiridium, Osmium, Iridium

Metals

Chromium, Gold, Iridium, Iron, Osmium, Palladium, Platinum, Rhodium, Tin, Titanium, Tungsten

Worked

Before and since the industrial age

Examples

California Gold Rush, 1848; Klondike, Yukon, 1896 to 1898; Witwatersrand, South Africa, an ancient placer

Sources

• Placer deposit. Wikipedia.
• Klondike Gold Rush. Wikipedia.

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