Description:Originally an igneous rock formed from magma produced by melting in the Earth's mantle. The magma was erupted at the Earth's surface as lava which solidified rapidly to form a fine-grained, dark igneous rock called basalt. The rock was then altered (metamorphosed) by heat and pressure within the Earth producing metabasalt.
Representing:Magma erupted during the Archean Eon, older than 2.5 billion years.
Where:Shield greenstone south
Original location:Yellowknife, Northwest Territories