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Post by stephan on Aug 5, 2015 11:33:18 GMT -5
They're tiger's-eye from South Africa. It can have natural color variations such as streaks of blue, red and even green (variegated Tiger's=eye); or occur in single hues, most commonly yellow-brown or blue. Most red tiger's-eye is yellow-brown material that's been heated to change its color but natural red material also occurs. The long-fibered pure blue material is called Hawks-Eye. Pietersite differs in both source and structure. It's presently found mainly in Namibia, not South Africa; and in China. As I posted previously it usually has a brecciated structure: a jumble of pieces that appear to have been shattered somehow, then rejoined in a patchwork of pieces, often of different colors. Look at the image link I posted and I think you'll see the difference. This is a yellow-blue Tiger's-eye cab from South Africa (not a great one!) for comparison: The difference in color between tigers eye and hawks eye is due to the fact that hawks eye still contains crocidolite (asbestos), whereas tigers eye has been completely replaced with silica.
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