Such concentrations are usually created by geological events, such as volcanic eruptions and tectonic plate shifts that steer hot metal-bearing fluids into upper, accessible parts of the Earth's crust, erosion, or massive sedimentary movements.

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Blocking the way up the stairs was a massive yellow iron metal door that sealed off access to the upper two floors of the house.

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They found a metal-like shine on the leaves, indicating that the upper and lower epidermis were dying.

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