Pyrite

Pyrite is an iron sulphide mineral with a hardness of 6-6.5. It's shiny yellow colour has earned it the name "Fool's Gold", as it can be mistaken for gold when found in seams of quartz. A dense mineral with substantial weight, it makes a very useful balancing tool, and its iron content makes it also useful for grounding. We sometimes use one in each hand to help ground and balance the left/right sides of the body, and the left/right hemispheres of the brain. Its sunny nature and golden sheen (rather difficult to photograph!) make it useful for working with the Solar Plexus chakra, and for grounding the Gold Ray (relating to structure and stability) into any of the energy bodies. Its nature is accordingly generally masculine, and is energising and stabilising in its actions.
It has been possible to find a rare combination of pyrite clusters that have been named "Isis and Osiris", where (as with Boji stones) one being smoother than the other. Melody writes of this combination that they will automatically align all the chakras and energy bodies of the aura; advance innate psychic and astral abilities; and promote retrieval of ancient mystical knowledge. She adds that they were used in Atlantean times to help maintain psychic energies and support material manifestation.