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 defined as any fuels that are formed under the earthâs surface by ancient plants and animals. This means there is not just one singular type of fossil fuel. This type of energy source is defined as non-renewable and is extracted from the ground.The process of extracting fossil fuels from the ground is quite complex, but these fuels are then used to power electricity and fuel for vehicles.The 3 primary types of fossil fuels that most people are familiar with include coal, oil and natural gas.There are a lot of concerns that arise when the issue of fossil fuels is raised. Many of these concerns center on environmental ramifications, supply demands, cost and a number of other issues.igh moisture is often required for coal fossil fuel to be formed. Now it is time to delve deeper into the topic of fossil fuels by further examining the pros and cons. Many of the concerns surrounding fossil fuels are not as black and white as they might seem.