<Tr> <Td> Appearance </Td> <Td> lustrous (at least when freshly fractured) </Td> <Td> lustrous </Td> <Td> several colourless; others coloured, or metallic grey to black </Td> </Tr> <Tr> <Td> Elasticity </Td> <Td> typically elastic, ductile, malleable (when solid) </Td> <Td> brittle </Td> <Td> brittle, if solid </Td> </Tr> <Tr> <Td> Electrical conductivity </Td> <Td> good to high </Td> <Td> intermediate to good </Td> <Td> poor to good </Td> </Tr> <Tr> <Td> Band structure </Td> <Td> metallic (Bi = semimetallic) </Td> <Td> are semiconductors or, if not (As, Sb = semimetallic), exist in semiconducting forms </Td> <Td> semiconductor or insulator </Td> </Tr>

Minerals that are predominately bonded by the covalent bond typically have this property