A charmstone is a mineral specimen that certain people believe has healing, mystical or paranormal powers. The mineral specimen may either be naturally occurring or hone from a natural stone; in some cases, the specimen may be entirely manufactured as in the case of certain Mayan pottery finds. For example, the Miwok and Pomo tribes of Northern California have left thousands of charmstones in the bed of Tolay Lake in Sonoma County. Charmstones are evidenced by the Shalagram and lingam in the Hindu tradition and by maban in the indigenous Australian tradition. Jigme Lingpa in the Vajrayana tradition wrote a treatise on charmstone usage which Namkhai Norbu mentions. Charmstones were used in prehistoric Native American cermonies for broader spiritual purposes including securing of productive harvests. Today it is popular among certain countercultures within Western society such as the new age movement, but is regarded as baseless by scientists and medical professionals.