Decorating with Minerals- Smokey Quartz
Location of mineral deposit: Hot Springs, Arkansas, United States
Description: Quartz crystals have been collected from the area around Hot Springs, Arkansas since the mid 1800’s. The actual extent of the quartz occurrences extends over 100 miles west into Oklahoma, however this site is the most well known and closely associated with occurrences of quartz crystals.
In his iconic “Gems and Precious Stones of North America,” published in 1892, George F Kunz describes the efforts of local farmers blasting in search of specimens in their spare time, and describes the flourishing trade in quartz crystals as mementos. So prolific were the specimens, that to this day few American mineral collections are without at least one example of this material.
This piece has been exposed to radiation in a man-made setting, causing its color to darken. Natural quartz always contains impurities, in the case of smoky quartz from Hot Springs, there is an occasional substitution of aluminum atoms for silicon atoms in the crystal lattice. Although this substitution only occurs on the order of several hundred per million atoms, it creates the condition wherein radiation exposure can alter the color of the quartz, by changing the way that its electrons absorb and release light waves. Although this darkening can occur naturally over geologic time periods with low radiation exposures, the same effect has been simulated by a brief, high-intensity exposure to an artificial radioactive source. The end result is the beautiful dark color seen in this specimen, which also incorporates multiple lustrous, sharply pointed crystals into a beautiful display piece.