Since each individual piece will change color at a different time, seeing the heating action is absolutely necessary. You can modify the basic process to achieve different effects, depending on the quartz source. In some instances, you might only achieve a quartz color by first destroying the existing color center.
This requires heating the crystal until it’s clear or white at temperatures up to 550 ° F. If you exceed this temperature, you risk creating an opaque, opalized stone. In other words, the quartz turns to a milky consistency resembling a common opal. If heating to 550 ° F doesn’t achieve the quartz color you want, try increasing the radiation dosage or subject the work piece to a different type of irradiation. For example, a quartz that goes to a straw yellow color on cobalt 60 might turn canary when exposed to electrons. Again, the color you might achieve depends on the material’s origin.
Below, you’ll find some results and individual treatment processes. All quartz can be irradiated to create the morion variety of smoky quartz. Additionally, all quartz will turn a blackish or brownish color on exposure to 0.5 to 1.5 mrd of cobalt 60, gamma, X-ray, or electron radiation. If that’s your goal, first irradiate then separate the lighter ones for re-irradiation at a higher dosage. Heat the stones that come back opaque black in a household toaster oven until you reach the desired shade. Except for this post irradiation heating step, the lab process involves little heat or static electricity. The maximum temperature the quartz will be exposed to during the irradiation process is 400 ° F. Arkansas Quartz (USA) I tested stones from various areas of this deposit. After testing stones from numerous locations in Brazil, the United States, and other nations, I found that, apparently, all hazy quartz with silk-like inclusions, no matter what intensity, will treat. Common results ranged from various yellows, an occasional orange cast, to an occasional greenish cast. In some cases, you can cook out the silk through pre-irradiation heating. In other cases, you can dissolve it during the irradiation process. You can even observe the lessening of the silk in the final heating step. However, some silk won’t dissolve during this heating process. This material seemed to reach its maximum color saturation at a dosage of 60 mrd. Again, different types of radiation produce different shades of color. Controlling Your Milky Quartz Color Results During Heating. During the final heating process, you can control the color somewhat. After you’ve irradiated the stones, spread them evenly on your toaster oven rack or a perforated baking sheet. (You must allow air to circulate freely around the stones, so don’t place them on a regular cookie sheet). Set your toaster oven to maximum temperature, then wait patiently. By continuously observing through the glass door, you’ll see the stones change color from an opaque black.
Remember, each stone may change at a different time. Therefore, size grade and heat stones of one size together to operate more efficiently. Keep in mind that most ovens reach hotter temperatures front to back. You might try putting larger crystals on the last row to better observe them.
So, while they’re still heating, you can remove the faster turning smaller crystals in the front row. Starting from a cold oven, expect to wait about two to eight hours for the crystals to turn. The transition can go from opaque black to slightly transparent brownish black, to greenish yellow, to canary yellow. This material changes slowly, so you have plenty of time to remove them at the desired color.