“One of the wilder proselytizers, a Scandinavian geologist Henrick Steffens, was said to have stated that ‘The diamond is a piece of carbon that has come to its sense.’ To which a Scottish geologist, probably John Playfair gave the legendary reply, ‘Then a quartz, therefore, must be a diamond run mad.”

“One of the wilder proselytizers, a Scandinavian geologist Henrick Steffens, was said to have stated that ‘The diamond is a piece of carbon that has come to its sense.’ To which a Scottish geologist, probably John Playfair gave the legendary reply, ‘Then a quartz, therefore, must be a diamond run mad.”

— Richard Holmes