Pyrolusite

Pyrolusite is a black mineral made mainly of manganese dioxide, and an important ore of manganese. Wikipedia describes a metallic lustre, a streak of black to bluish-black and a habit of soiling the fingers, and says the name comes from Greek words for fire and to wash, because it was used to take tints out of glass. Hall describes large, shiny, fan-like growths on a brown matrix, or granular masses, in silver, black, blue or dark grey, from the United States, Britain, Brazil and India. Hall associates it with restructuring energies, with transformation, with confidence and determination, and with a barrier against negative energy and psychic interference, and suggests keeping a piece in a meditation space. Hall notes that its delicate construction makes some pieces unsuitable for wearing. Hall also says it treats bronchitis and strengthens eyesight; these are that author's claims, and he advises an indirectly made elixir rather than placing it on the body.