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A semi-precious variety of quartz ranging in colour from light greyish brown to nearly black.
- ‘Quartz is colourless when pure but minute amounts of impurities or lattice imperfections give rise to varieties such as amethyst, cairngorm, rose quartz, and smoky quartz.’
- ‘They collected several pegmatite pockets in which topaz was associated with both clear and smoky quartz, microcline, albite, muscovite, fluorite, and cassiterite.’
- ‘Blue hexagonal beryl crystals and colorless, pale green, or blue topaz are found in cavities associated with microcline, smoky quartz, tourmaline, and, rarely, fluorite.’
- ‘The amazonite occurs in miarolitic cavities in granite as single crystals and crystal groups and is often associated with other minerals, especially albite and smoky quartz.’
- ‘One specimen of smoky quartz, a poorly formed crystal about 1.5 inches long, sitting alone in a cavity, was coated with gray-green clinozoisite prisms, which also formed inclusions.’
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