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Obsidian

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by

Ngoc Vo

on 30 October 2013

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Transcript of Obsidian

Obsidian
Obsidian rocks are igneous rock that form when lava cools quickly above ground.
what does it look like??
Some common obsidian colours include black, dark grey and greyish black.The colour of obsidian is related largely to the degree of crystallinity of the glass. Obsidian is an extrusive rock that cooled very rapidly without forming crystals. As a result, obsidian has a smooth, shiny texture of a thick piece of glass. It can contain small bubbles of air that are aligned along layers created as the molten rock flows before being cooled. These bubbles can produce interesting effects such as a golden sheen, or rainbow sheen. In the black glass, it can produce a blotchy or snowflake pattern known as the Snowflake Obsidian.
Where it is found in the world?!?
It can be found in Armenia, Canada, Chile, Greece, Iceland, Italy, Mexico, Peru, United States, Argentina and also in the locations that experienced ryholitic eruptions.
How obsidian is formed
It is formed from rapid cooling of felsic lavas, high in silica and aluminium. Obsidian is an extrusive igneous rock, formed from the extremely rapid cooling of felsic lava which includes arthoclase, quartz, and mica. Obsidian is a volcanic glass, meaning that the mineral constituent.
Uses of this rock?
The first use of obsidian was used as a cutting tool. People then discovered how to break the obsidian to produce cutting tools to a variety of shapes. Obsidian was used to make knives, arrow heads,spear points, scrapers and many other weapons and tools.
What type of rock is this?
Here is a video that will tell you more about the Obsidian rocks and interesting facts about them. Hope you enjoy. :)
Full transcript