Black Quartz


Staff member
Jun 3, 2020
Black Quartz is a variety of Quartz that ranges in clarity from almost transparent to almost opaque black crystal. The color is a result of free silicon formed from the silicon dioxide due to natural irradiation. It usually occurs in intrusive igneous rocks and high-grade metamorphic rocks.

The color of smoky quartz is caused by irradiation and traces of aluminum built into its crystal lattice. Aluminum replaces silicon to form a AlO4 group instead of SiO4. Small univalent cations (H+, Li+ or Na+) are built into the lattice to compensate for the imbalance of charge in the lattice. High energy radiation transfers the extra electron from AlO4 to the cation, and a color center is formed. H+ interferes with this process, and higher concentrations of built-in hydrogen inhibit the formation of color-centers.

Synthetic Black Quartz crystals
The smoky Quartz will lose its color when heated to around 200°C, and the color will return when the crystal is irradiated with x- or gamma-rays. The colorless quartz is artificially irradiated to sell it as smoky quartz.

Radiation hazard of Black Quartz
The Black Quartz is safe and there is no radiation hazard associated with it. Irradiating a crystal will cause some energy to be stored in the crystal structure which typically results in a change in color.
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Syed Muhammad

Jun 22, 2020
Didn't know that we had to develop synthetic black quartz crystals despite of quartz being the most abundant mineral on the planet

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