Granular crystalline mass of green potassium-iron Arrojadite, the most common Arrojadite found mostly in pegmatites. It is a primary phase and usually will not yield secondary phosphates. The type locality is shared between Nickel Plate pegmatite near Keystone, SD and the Serra Branca south of Pedra Lavrada and named after the Arrojado Ribeiro Lisboa a Brazilian geologist. It forms a series with dickinsonite, which contains manganese.
