One must also be aware that many stones, especially quartz minerals are often altered . Also keep in mind that there are conflicting names or definitions used for stones, one of the most complex being onyx . Many metal beads are made from minerals, including gold . Some stone beads have a long history and are still highly valued, such as the Pumtek. Some even come from outer space .
Some people believe that stones have mystical powers.
This idea is examined in light of the craze for mala or power beads .