Workers in this unit group prepare ores, stone and other minerals for distribution or further processing. Their functions include: drilling holes and driving wedges into quarried stone to break it into slabs or blocks; operating machines which crush and break lumps of mineral (except chemicals) to required size; operating grinding mill to pulverise stone and mineral-bearing ores; operating batteries of jigs or flotation machines to separate mineral from gangue; tending equipment which precipitates gold or silver from cyanide solution onto zinc; tending gravity device to separate slate and rock from coal; performing related tasks.