What is the hardest rock and what is its compressive strength (PSI)?
Diamond, since it is a natural mineral, would be considered a 'rock.' Diamond has a bulk modulus (reciprocal of compressibility) of 443 GigaPascals (GPa). One GigaPascal is equal to 14503.77 PSI. Therefore, the incompressibility of diamond is about 6.425 million PSI or 437,200 Atmospheres.
Diamond was once thought to be the hardest and the most incompressible material on earth, either natural or man-made. Although diamond is still considered the hardest, the bulk modulus of the metal osmium has recently been found to be 476 GPa. That is over 7% more incompressible than diamond, but it is never found pure enough in nature to challenge the diamond.
Scott Wilber, President, ComScire - Quantum World Corporation
Our server costs have gone up and our advertising revenue has gone down. You do the math! If you find our site useful, consider donating to keep us going. Thanks!
'You cannot hope to build a better world without improving the individuals. To that end each of us must work for his own improvement, and at the same time share a general responsibility for all humanity, our particular duty being to aid those to whom we think we can be most useful.'