| 31. | Tourmaline is notable for exhibiting strong pleochroism.
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| 32. | Brazilianite also found with tourmaline and feldspar.
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| 33. | Matthew Forster Heddle found the quarry a good source for the minerals tourmaline and beryl.
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| 34. | The inventor of a new polarizing medium, as an efficient substitute for the Tourmaline.
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| 35. | "There's a growing interest in colored gemstones like citrine and pink tourmaline.
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| 36. | Portnoy was keen to find something more unusual, a tourmaline or perhaps some green apatite.
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| 37. | Another highly valuable variety is chrome tourmaline, a rare type of dravite tourmaline from Tanzania.
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| 38. | Another highly valuable variety is chrome tourmaline, a rare type of dravite tourmaline from Tanzania.
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| 39. | Tourmaline also occurs in some aplites.
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| 40. | Associated minerals include beryl, phenakite, herderite, tourmaline, muscovite, fluorite and quartz.
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