Plural of graphite; plural instances or forms of the crystalline carbon mineral used in pencils, lubricants, and electronics.
From graphite (German 'Graphit' from Greek graphein 'to write') plus -s pluralizing suffix. The name stuck despite graphite being carbon, not lead.
Graphite's unique structure — flat sheets that slide past each other — is why pencils feel slippery and graphite works as a lubricant; same atoms, different arrangements!
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