Is obsidian rough or smooth?

Is obsidian rough or smooth?

Obsidian is an extrusive rock that erupted out of a volcano. Most volcanic rocks are rough and jagged because they contain gas bubbles. But obsidian is smooth because it contains mostly of glass.

Is black obsidian a hard stone?

As a type of volcanic glass, obsidian is hard, amorphous, and brittle. It doesn’t have the typical cleavage of other gemstones, plus its conchoidal fracture and acute edges when broken allow it to form very sharp and smooth edges. Pure black obsidian can be quite rare. See this pendant here.

How can you tell real obsidian?

Examine the obsidian’s general presence. It has a distinctive appearance of smooth glass. Obsidian is a frozen liquid that contains small amounts of mineral impurities. See the color Because pure obsidian is usually dark, on rare occasions it may also be almost white.

Is obsidian light or heavy?

Pictures? Obsidian is as heavy as any other average stone, since it is quartz, so if it is light weight, it is not obsidian. Very few minerals are light weight, especially dark minerals, none that I know of.

What are the characteristics of obsidian?

Origin and properties. Though obsidian is usually dark in color, similar to mafic rocks such as basalt, obsidian’s composition is extremely felsic. Obsidian consists mainly of SiO 2 ( silicon dioxide ), usually 70% or more. Crystalline rocks with obsidian’s composition include granite and rhyolite.

What happens when water is added to obsidian?

This transformation of obsidian is accelerated by the presence of water. Although newly-formed obsidian has a low water content, typically less than 1% water by weight, it becomes progressively hydrated when exposed to groundwater, forming perlite .

What did the Mesoamericans use obsidian for?

Pre-Columbian Mesoamericans’ use of obsidian was extensive and sophisticated; including carved and worked obsidian for tools and decorative objects. Mesoamericans also made a type of sword with obsidian blades mounted in a wooden body.

What is the difference between intrusive and intrusive obsidian?

Extrusive formation of obsidian may occur when felsic lava cools rapidly at the edges of a felsic lava flow or volcanic dome or when lava cools during sudden contact with water or air. Intrusive formation of obsidian may occur when felsic lava cools along the edges of a dike.