Plattnerite

Plattnerite is an oxide mineral and is the beta crystalline form of lead dioxide (β-PbO₂), scrutinyite being the other, alpha form. It was first reported in 1845 and named after German mineralogist Karl Friedrich Plattner. Plattnerite forms bundles of dark needle-like crystals on various minerals; the crystals are hard and brittle and have tetragonal symmetry.