Carbon (C) is known in three different conditions—transparent and crystallized as diamond, scaly and crystalline as graphite, and amorphous as lamp-black, charcoal, soot, etc. These different forms, though chemically identical, vary in hardness, specific gravity and other physical properties. Analysis of the crystal structure of diamond and graphite by means of X-rays shows the different atomic arrangement in the two minerals (p. 19 and Fig. 6). In graphite the atoms are arranged in layers that are further apart than in diamond, and this is held to account for the scaly nature of graphite—in each layer, however, the atoms are closely linked so that each flake of graphite breaks up into smaller and smaller flakes, a property on which the value of the mineral in lubrication is based. The diamond structure, on the other hand, has great strength and compactness which are reflected in the physical properties of the mineral.
KeywordsIgneous Rock Prismatic Crystal Closed Tube Hydrous Silicate Aluminium Silicate
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