Smoky Quartz

Smoky quartz is a quartz variety, brown to black in colour, ranging from almost fully transparent to nearly opaque. Wikipedia explains that its colour comes from natural gamma radiation in the surrounding rock acting on aluminium impurities in the crystal. Heating above about 200 to 300 °C, or ultraviolet light, fades it, sometimes to a pale yellow, and some heated smoky quartz is sold as citrine. Crystals that grew in pegmatites or alpine fissures are usually coloured evenly. Of little historical note in the past, it is now a popular gem and collector's crystal, and flat panes of it served as sunglasses in twelfth-century China. Hall counts it among the most effective grounding stones, calls it protective, and says it also raises the vibration during meditation. She associates it with easing stress, fear and nightmares, with clearing the mind for meditation, with scrying and with easing difficulties in communication. Cunningham, writing within his quartz entry, gives it a receptive energy, calls it a mood-lifter and has it worn for grounding and to help overcome depression and other negative feelings.