Obsidian Rock Facts

Obsidian Rock Facts
Obsidian is an igneous rock that forms when molten rock cools very rapidly. The result is a rock that cooled so fast, crystals did not get a chance to form. Obsidian is a volcanic glass with a smooth and uniform structure.
Interesting Obsidian Rock Facts:
Different varieties of obsidian rock get their names from their appearance.
The appearance of obsidian is based on the chemical composition of the magma that cooled to make the rock.
Obsidian is also known as "nature's glass" because of its glassy appearance.
When obsidian breaks, the fractures are very sharp which is why it was used as tools in the Stone Age.
Seventy percent of obsidian rock is made of silica.
Obsidian can only form near active volcanoes.
Sometimes obsidian is erupted directly from a volcano.
The best obsidian is formed underground near a volcanic vent because those rocks will have limited impurities.
Obsidian flows are so slow that often other obsidian flows will occur on top of each other causing a streaked appearance in the obsidian rock.
Tiny gas bubbles that trap water are a part of every obsidian rock.
Although most rocks that form in the Earth's crust are very old, obsidian is rarely older than 20 million years old which is young for a rock.
Obsidian goes through a process called devitrification whereby it turns from glass to a rock.
Obsidian is commonly used during surgical procedures because it is often sharper than traditional surgical tools.
Obsidian is used as a gemstone in jewelry.

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