According to the guide, the most valuable amethysts are those that are categorized as medium reddish purple with a slight tint of brown.. This rare amethyst commanded between $64.00 and $70.00 as of March 2014. At the same time, the least valuable amethysts were those that were very light purple in color.
Geology and Sources of Energy. by Steve Sharp, P.E. Some of our mineral resources can be taken out of the ground and used for fuel. Raw materials have two sources: they can be grown or they can be mined. Coal, oil and gas are collectively called fossil fuels, because they formed from organic (living) matter. Uranium is also a source of energy that is taken out of the ground. These fuels that are mined are called non-renewable resources, because we can't replace them.
Fossil fuels are energy resources that come from the remains of plants and animals. These remains are millions of years old. There are three fossil fuels: petroleum oil, natural gas, and coal. Fossil fuels, like coal, oil, and natural gas, provide the energy that powers our lifestyles and our economy.Fossil fuels power everything from the planes in the sky to the cars on the road. They heat our homes and light up the night.Theyre the bedrock we base our energy mix on. But they are a limited resource.ossil fuels, like coal, oil, and natural gas, provide the energy that powers our lifestyles and our economy. Fossil fuels power everything from the planes in the sky to the cars on the road. They heat our homes and light up the night. Theyre the bedrock we base our energy mix on.