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Brazil diamond deposits, geology, exploration, mining, use - Part X |
 | | By treating finely powdered carbonado with aqua regia a portion of the mineral matter constituting the ash may be dissolved out, the solution being found to contain iron and a little calcium, but no aluminum. |
 | | The hardness of carbonado not only equals that of diamond, but may even exceed it, and its hardness is supposed to be greater the less distinctly it is crystalline. |
 | | Carbonado cannot therefore be cut by ordinary diamond powder, or at least only with extreme difficulty; it forms a valuable cutting material for ordinary diamonds, and large quantities are used as a grinding material for this and other purposes, which require exceptionally hard material. |
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