| 11. | This disintegration of marcasite in mineral collections is known as " pyrite decay ".
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| 12. | The sulfides galena, sphalerite and marcasite are enclosed within the quartz / baryte.
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| 13. | Uranium minerals are found associated with iron and manganese oxide, marcasite and pyrite.
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| 14. | The narrower, modern scientific definition for marcasite as orthorhombic iron sulfide dates from 1845.
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| 15. | Marcasite in the scientific sense is not used as a gem due to its brittleness.
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| 16. | It occurs as a weathering product under acidic conditions associated with pyrite or marcasite decomposition.
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| 17. | It occurs in hydrothermal deposits associated with sphalerite, pyrite, chalcopyrite, barite and marcasite.
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| 18. | The black shales also contain high amounts of sulfides ( marcasite, pyrite ) and carbon.
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| 19. | He bought marcasite stones, mainly in Czechoslovakia, that were used by Paris milliners at the time.
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| 20. | Associated minerals include melanterite, epsomite, jarosite, gypsum, sulfur, pyrite, marcasite and limonite.
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