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Volcanic bombs

Part of Hall of Planet Earth.

Two volcanic bomb specimens. These rocks form when blobs of magma projectiles cool. These two have round-oval shapes and bumpy irregular surfaces. AMNH/R.Mickens

Volcanic bombs form during many eruptions. The patinas of reddish brown or bluish iridescence formed when the bombs’ outer layer reacted with the oxygen in the atmosphere.

Provided by Lava Beds National Monument and Jeff Dinnel, Tionesta, California