英文關鍵字
africa
aluminium
brazil
buried
cave
cavern
caves
chemical
chemistry
cobalt
copper
desert
egypt
element
fools
gold
industrial
industry
iron
lead
material
metal
metallic
metals
mine
mineral
minerals
mines
mining
mixture
ore
piece
precious
rare
raw
rock
rocks
shiny
silver
small
stone
stones
tin
titanium
valuable
zinc