Petroleumis a very important mineral. It gives us heat and light. It gives us power for our cars, planes, and ships. Also, it gives us power for machines of all kinds. How is petroleum formed? Scientists believe petroleum comes from the remains of plants and animals (Remains are what is left after a plant or animal has died.) What exactly is petroleum? Petroleum is a mineral that is a mixture of hydrocarbons. It is an oily liquid, which may be brown, green, or black in colors. The word "petroleum" comes from Greek. It means "rock oil". Crude (, ) oil is petroleum that comes directly from deep in the ground. It is then taken to a refinery. a refinery is a kind of factory to refine oil. At a refinery the crude oil is separated into many parts. From the refined petroleum we get important things, such as gasoline, kerosene, fertilizer, detergents and a lot of other useful things. In fact, there are thousands of such things that we can get. Petroleum really is of great value! This passage is most likely taken from   _  .
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