<p>Basalt (현무암)<br>Most of the Jeju mainland's surface is covered with basalt. It appears black to our eyes, but is colorful under a microscope. It is common here, but rare in South Korea. The oceanic crust, which accounts for 3/4 of the Earth's surface, is entirely covered with basalt. The reason it is black is because it contains an ore called pyroxene, and the reason the holes are here and there on the basalt is gas inside the lava escaped  from the lava  when it solidified on the ground.When the gas was in a molten state underground, the pressure was high so it could not escape, but on the ground the pressure was lowered and escape was possible.If basalt goes through the process of weathering it could turn red or purple. When basalt cools slowly after receiving high heat underground, it becomes gabbro.<br>The stone pot used to make stone pot rice is a man-made gabbro.</p>
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