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Why is obsidian so smooth?
Obsidian is a natural glass, often formed in volcanoes. It has a smooth glassy texture, and will commonly fracture with a curved fracture plane called conchoidal fracture, after the resemblance to the shape of a shell. Usually black because of the trace iron content.
How was the rock obsidian made?
Obsidian is formed when lava cools very quickly, typically within a few hours, preventing crystallization. This rapid cooling prevents mineral crystals from forming, resulting in a smooth, glassy texture.
What is the difference between obsidian and coal?
Obsidian is a naturally occurring volcanic glass formed from rapidly cooling lava, while coal is a sedimentary rock made from compressed plant matter. Obsidian is usually black or dark in color and has a glassy texture, whereas coal is black or brown and can be shiny or dull depending on the type. Observably, obsidian is formed from volcanic activity, while coal is formed over millions of years from plant decomposition.
What does obsidian and coal have in common?
Obsidian and coal are both naturally occurring substances derived from volcanic activity. They are both used as raw materials in crafting and construction. Additionally, both obsidian and coal have been historically significant resources for human societies.
How do you tell the difference between Obsidian rock and Coal Flint rock?
Obsidian is a natural volcanic glass that is typically black and glassy in appearance, whereas coal is a sedimentary rock that is typically black and dull in appearance. Flint is a hard, sedimentary rock that often has a dark grey or black color with a smooth or waxy texture, whereas coal is formed from plant matter and is combustible.
What texture of obsidian?
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.
What texture does obsidian have?
A glassy texture.
What is the texure of obsidian?
Obsidian is an igneous rock with a glassy texture. Its texture is also called hyaline, the Greek word for texture.
What are rocks that have a glassy texture called?
Obsidian
How does obsidian get its unusual texture?
The texture of a rock depends on the rate that it cools. Obsidian cools so quickly that no crystals can form, therefore giving it a glassy texture.
Describe the texture of obsidian?
Obsidian is a hard, dark volcanic rock that is formed by the rapid solidification of lava. Its texture is glassy and shiny black.
Which characteristic provides the best evidence that obsidian rock formed in an extrusive environment?
The glassy texture of obsidian is the best evidence that it formed in an extrusive environment. Obsidian is rapidly cooled lava with no time for crystal growth, resulting in a smooth, glass-like texture.
What is the texture of the very finest grained rocks called?
vitreous or glassy (obsidian)
Where does obsidian rock cools down?
Obsidian is an glassy, extrusive, igneous rock that is found in areas that have experienced rhyolitic eruptions. Obsidian is formed when the rhyolitic lava comes into contact with water. This quick-cooling results in the glassy texture of obsidian.
What is a glassy rock?
Glassy rocks are rocks that have cooled and solidified quickly, without forming crystals. This rapid cooling prevents mineral crystals from growing, resulting in a smooth and glass-like texture. Obsidian and pumice are examples of glassy rocks.
What is smooth glassy lava called?
Smooth glassy lava is called obsidian. It forms when lava cools quickly, preventing crystals from forming, resulting in a glassy texture. Obsidian is typically black in color but can also appear in various shades of brown, green, or red.
What is considered to be volcanic glass?
Obsidian, due to its glassy texture made from the super-cooling process.
