Material properties of diamond 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 high as 90–225 GPa depending on the crystal orientation. The anisotropy of diamond hardness is carefully considered during diamond
Mineral spa Mineral spa Mineral spas are spa resorts developed around naturally occurring mineral springs. Like seaside resorts, they are mainly used recreationally although they also figured prominently in prescientific medicine. Spas were used for millennia for their purported healing or healthful benefits to those wealthy enough or close enough to partake of their waters. This was called a mineral cure and gave let to such phrases as "taking a cure" and "taking the waters". There has always been a mixture of recreational and medicinal connotations involved, from rest and relaxation, stress relief, and convalescence to more specific notions such as humorism.