Smoky quartz is a variety of quartz (SiO₂) distinguished by its gray to brown coloration, caused by natural radiation interacting with trace amounts of aluminum in the crystal lattice. This mineral forms in igneous and metamorphic environments and is chemically identical to clear quartz, with color variations resulting from its geologic history.
Features:
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Composition: Made of silicon dioxide, smoky quartz crystallizes in the trigonal system and typically forms six-sided prisms ending in pyramids.
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Coloration: The smoky appearance is due to natural gamma radiation altering aluminum impurities within the quartz structure, creating color centers that absorb light.
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Formation: Commonly found in granitic pegmatites, alpine-type fissures, and hydrothermal veins. Notable sources include Brazil, Switzerland, Colorado (USA), and Madagascar.
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Physical Properties: Smoky quartz is durable (Mohs hardness 7), exhibits a vitreous luster, and can range from nearly transparent to almost opaque depending on radiation exposure.
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Educational Value: Useful for illustrating mineral color centers, crystal growth, and the effects of natural radioactivity on mineral appearance.
Smoky quartz is a classic mineral for collections, display, or educational use in crystallography and geochemistry.
