Die Welt der Edelsteine - Gemstones
Aragonite.. Aragonite and the more common mineral Calcite are polymorphous to each other. Although Aragonite and Calcite contain the same chemical composition, they differ in crystal structure. Aragonite forms orthorhombic crystals, whereas Calcite forms trigonal crystals. Since the true identity of microcrystalline forms of Aragonite or Calcite may not be known, they may be mislabeled as the wrong mineral.
Cinnabar (mercury sulfide) is the single most toxic mineral to handle on Earth. The name means dragon's blood. It is the main ore of mercury, forming near volcanos and sulfur deposits. Cinnabar may release pure mercury if disturbed, causing tremors, loss of sensation and death. From the Middle Ages to late 1700s, being sent to work in Spanish mines containing cinnabar formations was a death sentence. Cinnabar was widely used in China for ornamental dishes with intricate carvings.