Rock salt
The diamond among salts.
The oldest salt in the world, which was created under extreme pressures has a perfectly aligned crystal lattice. This gives the salt the appearance of a diamond. It breaks off in cubes and used to be thought of as a special power stone.
It was called „Whites Gold“, because it was weighed against gold. One kilogram of rock salt was worth one kilogram of gold. In the Middle Ages, the use of rock salt was a privilege reserved for the nobility.
chemical analysis: Rock salt (PDF, 761kb)