Рет қаралды 14,338
THERE ARE VARIOUS TYPES OF ( Mohs hardness )
DUE TO BEING IN NATURE FOR BILLION YEARS
AND IT IS NECESSARY TO STUDY A LOT! NOT EVERY LAND OR MOUNTAIN WAS VOLCANO IN THE PAST! NOT EVERYONE CAN STUDY! FOR THE MATERIAL IS NEEDED! THE THEORY EVERYONE KNOWS! MORE PRACTICE NOT !