What's medical stone?

Medical stone, alias: longevity stone, health stone, refining rocks, horse teeth sand, bean residue stone, is a natural drug ore.  Medical stone contants the necessary element for the human body, such as Constant element: potassium, sodium, calcium, magnesium, phosphorus and trace element: zinc, iron, selenium, copper, strontium, iodine, fluorine, partial silicic acid. Maifanite belongs to volcanic rocks. Maifanshi is considered to be 50-75.5 million years ago, volcanic lava is buried underground, after the volcanic high humidity, hot spring acidic substances generated by the crustal changes and the pressure generated by the formation. It can be inferred that Maifan stone produced in the volcanic zone.