Quartz minerals are associated with all other quartz varieties, including microcrystalline varieties such as Agate, Chalcedony, and Jasper. They are also commonly associated with Calcite, Fluorite, Hematite, Muscovite, Pyrite, Rutile, Spessartine Garnet, Topaz, and Tourmaline.
Natural Quartz vs Heat Treated Quartz
Much of the Quartz on the market is natural and enhanced only by cutting and polishing. The most desirable varieties are transparent, either clear as glass or with attractive prisms that sparkle in the light and cast rainbows. High quality Quartz is colorless or has a vivid color, while low quality is pale, dull and unremarkable.
Heat-treatments are common for Amethyst, Citrine, Prasiolite and Smoky Quartz. Heat-treatments mimic natural processes, by heating the quartz to a high temperature much as might happen if the Quartz was near a geothermal source. As the quartz heats, trace impurities begin to alter on an atomic level, with ions gaining and losing electrons, and the result is a change in color. By controlling the temperature, a low-grade Amethyst can be transformed into high grade Amethyst, Citrine or Prasiolite. All three of these crystals have iron impurities, the only difference is the heat level. Smoky Quartz has trace impurities of aluminum, instead of iron. The aluminum is affected by natural irradiation inside the earth, giving the quartz its smoky brown or grey coloring. Low-grade Smoky Quartz can be exposed to radium or x-rays to produce a more valuable vivid shade.
These heat-treatments can be done at a lapidary or even directly at the mine. From a scientific perspective, there is no way to distinguish between between naturally vivid and heat-treated crystals. But, if you know where the crystal came from, it is possible to make an educated guess. For example, Australia is known for having natural Smoky Quartz that are so dark they are almost black, so a Smoky Quartz from that country is more likely to be natural.
What’s the deal with all the Quartz names?
There are countless marketing names given to transparent and opaque Quartz minerals. For example, a Clear Quartz with Hematite inclusions may be called “Hematite Quartz,” “Scarlet Quartz,” “Strawberry Quartz,” “Tangerine Quartz,” “Elestial Quartz,” etc. There are no standard rules that govern marketing names. The most useful marketing names are those that indicate a specific deposit or specific inclusions. For example, Auralite 23, is a Quartz mineral that combines Amethyst with up to 22 other minerals and comes from a small deposit in Ontario, Canada. By contrast, Super Seven, is a Quartz mineral that combines Amethyst with up to 6 other minerals, and comes from a variety of small mines in Minas Giras, Brazil.
Some marketing names are purposefully obscure and target the healing crystal community, promising a rare stone with high-energy. In reality, these are typically lower-grade stones. For example, Azeztulite is a common opaque quartz that is not associated with any single location. It’s high price is justified solely by its purported energy and a story involving angelic beings. Likewise, “Green Amethyst” is often used in place of Prasiolite, because the name recognition helps drive the price up. In the USA, it against the Federal Trade Commission Guidelines to call Prasiolite “Green Amethyst,” nevertheless the practice is very common among wholesalers and retailers alike.