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.
Also as a fibrous mass (asbestos) and as a fibrous and very compact mass (nephrite jade). Cleavage: is perfect in two directions at close to 60- and 120-degree angles. Fracture is splintery to uneven. Specific Gravity is approximately 2.9 - 3.3 (very slightly above average for translucent minerals).