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.
There are two main methods to date a fossil. These are: 1  absolute dating methods that tell us the actual age (in years) of an object. 2  There are many absolute dating methods. 3  Nearly all of these methods make use of radioactive elements that occur naturally in various types of minerals and organic matter.here are two main methods to date a fossil. These are: 1  absolute dating methods that tell us the actual age (in years) of an object. 2  There are many absolute dating methods. 3  Nearly all of these methods make use of radioactive elements that occur naturally in various types of minerals and organic matter.