Galena

Galena is lead(II) sulfide, the chief ore of lead, also called lead glance. Wikipedia describes it as lead-grey and silvery. Hall describes small shiny masses, or larger granular and knobbly ones, in a metallic grey-lilac. Hall calls it a stone of harmony and a grounding stone, and says it aids holistic healing. These are Hall's claims, not established fact. Because galena is lead-based, Hall advises that any elixir be prepared using the indirect method and used only on the outside of unbroken skin. Wikipedia warns that swallowing or breathing in galena can be very toxic, and adds that kohl, an old cosmetic made from it, is now regarded as toxic. Wikipedia also gives its crystal system as cubic.