Physical, Chemical and Structural Properties of Amethyst

To help identify and classify Amethyst
Amethyst is a variety of quartz which naturally occurs in crystal form and is the most valuable form of quartz. The transparent prismatic crystals can be found in clusters as an incrustation (or druse) in a nodular stone, commonly known as a geode. Amethyst is unique in color, ranging in shades of purple from pale lavender or lilac to a deep intense purple. In jewelry, the most precious Amethysts are the ones with the deepest and densest variations while maintaining their transparency and luster.

Physical Properties:
Amethysts vary in shades of purple but can even include a reddish and milky purple quality. The purple color comes from the manganese in clear quartz. The presence of iron helps determine the intensity of the color. Amethysts could be very expensive but due to the wide-spread and numerous global deposits, it can be found very inexpensively. Not only can Amethyst range in color but it also ranges in transparency from very transparent to almost translucent but always maintains the glassy luster. With a specific gravity of 6.5 and hardness of 7 (Mohs' scale), real Amethyst is tough to distinguish from the synthetic one. In nature as a mineral, each crystal cluster differs from region to region and mine to mine. Gem experts can usually identify the region from which a particular specimen originated from the density of it's color, the cleavage, shape, crystal system and other physical characteristics which imply it's original context.

Chemical Properties:
The chemical name for Amethyst, Silicon Dioxide (SiO2), along with distinctive attributes relating to the color are representative of its chemical composition. Amethyst obtains the color through a combination of manganese impurities (Mn) and the existence of iron (Fe) in specific quantities. The color of each crystal is dependant upon the distribution of color-filled bands within it. These color bands are stable only at temperatures below 480 degrees Fahrenheit (248.9 degrees Celsius) so this semi-precious stone should be protected from extreme heat in order to prevent fading. Professional heating treatments (on the other hand) have been used on Amethyst to produce the popular gems known as Citrine and Ametrine (400 and 500 degrees Celsius). Many naturally occurring Citrines began as Amethyst and were created by being heated by exposure to lava and magma from nearby volcanoes and other magma containing bodies. Ametrine has become a popular semi-precious gem which is a product of being half Amethyst and half Citrine.