Shungite
Shungite contains a high percentage of carbon (up to 98%), including a form known as fullerenes, which are molecules composed entirely of carbon in the form of a hollow sphere, ellipsoid, or tube. The origin of shungite is still somewhat mysterious, but it is believed to have formed from the sedimentation of organic matter several billion years ago. Some theories suggest its carbon basis may even originate from ancient microorganisms. Shungite is known for its electrical conductivity due to its carbon content, which is unusual for most rocks. It has a Mohs hardness of 3.5-4, making it relatively soft but durable enough for various uses. Shungite is used in water purification due to its ability to absorb pollutants and heavy metals while also killing bacteria. While shungite is found primarily in Karelia, Russia, smaller deposits have been identified in other locations around the world, though none are as extensive or as high in carbon content as the Karelian deposits.