Mohs scale of mineral hardness
Seraphinite apparently acquired its name due to its resemblance to feathers due to its chatoyancy. Seraphinite is named after the biblical seraphs or seraphim angels. With some specimens the resemblance is quite strong, with shorter down-like feathery growths leading into longer "flight feathers"; the resemblance even spurs fanciful marketing phrases like "silver plume seraphinite." Seraphinite is generally dark green to gray in color, has chatoyancy, and has hardness between 2 and 4 on the Mohs scale of mineral hardness.