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| | DIAMOND - LoveToKnow Article on DIAMOND (Site not responding. Last check: 2007-10-11) |
 | | Diamantina is at present the most important district; it occupies a mountainous plateau, and the diamonds are found both on the plateau and in the river valleys below it. |
 | | The mountains consist here of an ancient laminated micaceous quartzite, which is in parts a flexible sandstone known as itacblumite, and in parts a conglomerate; it is interbedded with clay-slate, mica-schist, hornblende-schist and haematite-schist, and intersected by veins of quartz. |
 | | At So Joho da Chapada, in Minas Geraes, diamonds occur in a clay interstratifiecf with the itacolumite, and are accompanied by sharp crystals of rutile and haematite in the neighborhood of decomposed quartz veins which intersect the itacolumite. |
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