Diamond. a very hard material that is the hardest substance ever, or at least discover to be the hardest substance on EARTH THAT IS
The hardest substance in a rock would be the hardest mineral of which the rock is composed.
diamonds are the hardest
Diamonds are the hardest mineral and the agate is the secod hardest mineral.
The name of the hardest solid is a diamond; it is the hardest object known to humankind.
From what I hear, One is the hardest & Master of Puppets is second hardest.
The third hardest gemstone is ruby and then the fourth hardest is emerald.
yes.
Diamond is the hardest precious stone
the hardest i can think of is "What is the answer to this question?"
Expert is the hardest.
Madagascar is the hardest to fake.
More information is needed to properly answer this question. The top 10 hardest firms in the world is too broad. Do you mean the hardest firms to get hired by, the hardest firms to work for, the hardest firms to sue?