Material properties of diamond to a very large kinetic energy barrier, diamonds are metastable; they will not decay into graphite under normal conditions. Material properties of diamond Diamond is the allotrope of carbon in which the carbon atoms are arranged in the specific type of cubic lattice called diamond cubic. Diamond is an optically isotropic crystal that is transparent to opaque. Diamond is the hardest naturally occurring material known. Yet, due to important structural weaknesses, diamond's toughness is only fair to good. The precise tensile strength of diamond is unknown, however strength up to 60 GPa has been observed, and it could be as
Mineral they help to define the limits of what constitutes a mineral proper. The formal Nickel (1995) definition explicitly mentioned crystallinity as a key to defining a substance as a mineral. A 2011 article defined icosahedrite, an aluminium-iron-copper alloy as mineral; named for its unique natural icosahedral symmetry, it is a quasicrystal. Unlike a true crystal, quasicrystals are ordered but not periodic. Minerals are not equivalent to rocks. A rock is an aggregate of one or more minerals or mineraloids. Some rocks, such as limestone or quartzite, are composed primarily of one mineral—calcite or aragonite in the case of limestone, and