Smoky quartz clusters (0.4-3kg) from Corintho, Minas Gerais, Brazil (BESTSELLER!)

Smoky quartz is a variety of quartz. The color is smoky brown to almost black, translucent. Very dark variants are called morion. Smoky quartz is most commonly found in cavities in intrusive rocks and high-grade metamorphic rocks. In sedimentary rocks and volcanic rocks, smoky quartz is rare. Locations include the Alps, Brazil, Russia, Mexico, India, Ireland, Zimbabwe, Afghanistan, and the USA. The color of smoky quartz is caused by aluminum in the crystal lattice in combination with ionizing radiation. The aluminum replaces the silicon in the crystal structure, forming the complex [AlO4-] instead of [SiO4]. To compensate for the resulting charge difference, small monovalent cations such as hydrogen, lithium, or sodium are simultaneously incorporated into the crystal structure during the growth of the crystal. Under the influence of ionizing radiation, the electron from the [AlO4-]-complex moves to a cation, creating a color center. This process normally occurs only below 50°C. At higher temperatures, the breakdown of the color centers occurs faster than their formation. The source of the ionizing radiation is usually potassium-40, the surrounding rock. The color of smoky quartz thus develops long after the crystals have formed and can take several million years. This is also the reason why most smoky quartz forms in feldspar-rich rocks such as granite. When heated above 200°C, smoky quartz will lose its color. Irradiating clear quartz (rock crystal) with X-rays or gamma rays almost always produces smoky quartz. The method is therefore used to turn colorless quartz into smoky quartz. In ancient times, this stone warned soldiers in battle when it darkened. Smoky quartz is still used for rosaries and crucifixes. A number of healing properties are attributed to smoky quartz; it is said to help with digestive issues, stress, sadness, and assist with a desire to conceive. According to various literature, the mineral is associated with the zodiac sign: Libra.