Pietersite

Pietersite is a trade name given to one kind of chalcedony, itself a variety of quartz (silicon dioxide), valued as a decorative stone for its broken-up, brecciated structure and a restless, swirling sheen. Its colours run from reddish brown through blue-grey to a shimmering yellow: Chinese stones are mostly reddish brown with patches of blue and yellow, while Namibian ones are mostly blue-grey. Wikipedia dates its first description to Namibia in 1962 and its discovery in Henan Province, China, to 1966. Many accounts call it a broken-up hawk's eye or tiger's eye, but Wikipedia calls this inaccurate: the stones are mineralogically alike and take their sheen from the same fibrous mineral, crocidolite, yet pietersite is not a broken form of either. Hall, who also calls it the tempest stone for its tie to the storm element, describes it as mottled and iridescent, usually small and tumbled, and easy to come by. She associates it with spiritual journeying and vision quests, moving meditation, intuition and precognition, and with walking one's own truth and telling true words from false. She also says it releases beliefs that other people have imposed, backs up willpower, and gives strength and support.