Smoky quartz is a quartz variety. The smoke color is brown to almost black, translucent. Very dark variants are called morion. Smoky Quartz is most common in cavities in intrusion rocks and high-grade metamorphic rocks. In sedimentary rocks and extrusive is smoky quartz rare. Sites in include the Alps, Brazil, Russia, Mexico, India, Ireland, Zimbabwe, Afghanistan and US The color of smoky quartz is caused by aluminum in the crystal lattice, in combination with ionizing radiation. The aluminum to replace the silicon in the crystal structure in which the complex [AlO4-] is formed in lieu of [SiO4]. For example, the resulting charge difference to compensate for times there is the growth of the crystal at the same time small monovalent cation of hydrogen, lithium or sodium incorporated into the crystal structure.
Under the influence of ionizing radiation, the electron moves from the [AlO4 -] – are complex to a cation, and creates a color center. This process occurs normally only below 50 ° C. At higher temperatures, the decomposition of the color centers place more rapidly than the production thereof. The source of the ionizing radiation is usually potassium-40, the surrounding rock. So the color of smoky quartz occurs long after the crystals are formed and can take several million years, this is also the reason most cairngorms in feldspar rich rocks such as granite genesis.
When heated above 200 ° C will smoky quartz lose its color. Irradiating clear quartz (rock crystal) with X-rays or gamma radiation produces almost always in smoky quartz. The method is then also used to make of colorless quartz smoky quartz. In ancient times this stone warned the soldiers in battle as he darkly colored. Smoky Quartz is still used for rosaries and crucifixes now. Some medicinal effects is awarded to smoky quartz; it would help prevent digestive problems, stress, grief and help a child. According to various literature belongs to the mineral in the constellation Libra.