Crude oil is a mineral oil consisting of a mixture of hydrocarbons of natural origin, yellow to black in color, of variable specific gravity and viscosity.

• Crude oil type has a unique composition and is a complex mixture containing many thousands of hydrocarbon molecules of different shapes and sizes.
  
   
• Crude oil varies radically in its properties, namely specific gravity and viscosity. Depending on the chemical nature of its chief constituents, crude oil is classified as paraffin base, asphaltic base, or mixed base.
  
   
• A mixture of hydrocarbons existing in the liquid state found in natural underground reservoirs often associated with gas. A naturally occurring, oily, flammable liquid composed principally of hydrocarbons. Crude oil is occasionally found in springs or pools but usually is produced from wells drilled beneath the earth\'s surface.
   

• Crude oil is the mixture of petroleum liquids and gases (including impurities such as (sulphur) that is pumped out of the ground by oil wells.