<Tr> <Th> Crystal habit </Th> <Td> Cubes and octahedra, blocky, tabular and sometimes skeletal crystals </Td> </Tr> <Tr> <Th> Twinning </Th> <Td> Contact, penetration and lamellar </Td> </Tr> <Tr> <Th> Cleavage </Th> <Td> Cubic perfect on (001), parting on (111) </Td> </Tr> <Tr> <Th> Fracture </Th> <Td> Subconchoidal </Td> </Tr>

Name the chemical formula of zinc blende and galena