Obsidian
From Geology Wiki
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| Pronunciation | Ob-Sid-Eee-An |
|---|---|
| Rock/Mineral | Rock |
| Type | Igneous |
| Cleavage | Conchoidal |
| Hardness | 5.5 |
| Streak | White |
| Lustre | Vitreous |
| Specific Gravity | 2.6 |
| Chemical Compound | SiO2 |
Obsidian is a rock that is formed when lava cools very quickly. Lava can cool quickly if it flows into an ocean or a deposit is rained upon. Obsidian has a glass-like texture and is sometimes known as Volcanic Glass. It is very durable. When cut properly, Obsidian blades can become paper-thin and be used as arrowheads and surgical tools.
Obsidian is not a mineral, because it has certain "rockish" properties, but is sometimes called a mineroid (Half-half). Pure Obsidian is usually black, but there are some varieties, such as Snowflake Obsidian and Rainbow Obsidian that have different molecular composures and form with colors such as green, white, red, and blue.
Iron and Magnesium give Obsidian its dark, usually black color. There is a variety of obsidian that is called snowflake obsidian. This variety has white splotches on it.
Obsidian has been previously used in history in things like arrowheads, used in trading, and other various tools.
