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The mineral graphite is an allotrope of carbon. It was named by Abraham Gottlob Werner in 1789 from the Ancient Greek ""to draw/write"", for its use in pencils, where it is commonly called lead (not to be confused with the metallic element lead). Unlike diamond (another carbon allotrope), graphite is an electrical conductor, a semimetal. Graphite is the most stable form of carbon under standard conditions. ",
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Refractive Index Reference - Filmetrics Composite
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