Basalt
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Basalt is an igneous volcanic rock, formed from metal-rich lava that cools at the surface of the earth or the bottom of oceans. Basalt is dark and very fine-grained, which means you can’t see crystals in the rock with the naked eye. Basalt is known for forming interesting shapes when lava is cooling. These shapes include tall pillar-like structures called columnar basalt, which form at the surface. Another shape is pillow basalt, which forms underwater. Once you see it, it’s easy to guess how pillow basalt got its name because it looks like stacked up pillows. Volcanic eruptions in Hawaii today provide an excellent example of basalt formation.
Where is it found?
In Manitoba, basalt is found on the Canadian Shield in areas called greenstone belts. Greenstone belts are large areas of rock that formed around ancient volcanic islands. These belts occur in the areas of Oxford-Knee Lake, Gods River, Cross Lake, Island Lake and many others. The basalt rocks at Oxford Lake are over 2.8 billion years old, and are some of the oldest rocks in Manitoba! In the forests of the southern Whiteshell area, you can find fantastic examples of pillow basalt, and in Flin Flon, most of the city’s rolling hills are basalt formations. In Manitoba, basalt rocks are often found within or near ore deposits of minerals like gold and copper. Many mines hosted in basalt rocks and greenstone belts provide jobs, start and sustain communities in rural and northern Manitoba, and contribute to our economic development.
