What is a variable speed drive? A variable speed drive is a piece of equipment that regulates the speed and rotational force, or torque output, of an electric motor. The background and technology. There are millions of motors in use in industry and offices around the world.
The specific gravity for Obsidian is 2.35, it's refractive index is 1.48-1.51, and it's double refraction is None. History Obsidian is named after a Roman, Obsius.
Black Obsidian has been used since Paleolithic times for making tools and weapons because it holds a sharp edge. Black Obsidian Geological Description: Obsidian is a glassy, silica rich rock formed from lava with a hardness of 5 to 5.5. It is an amorphous stone meaning that its structure contains no regular geometric pattern. Obsidian is found in South America, Japan, Mexico, Afghanistan, and parts of the United States.