Purple "Pimpleback" Shell 8mm Faceted Coin Bead - 15-16 Inch Shape_Coin is desired by some collectors

is desired by some collectors as proof of a natural stone

Gem Silica is the rarest and highest form of Chrysocolla

Andalusite is a fascinating aluminum silicate mineral known for its strong pleochroism—the ability to display multiple colors from different angles

but its identity is complicated

Purple "Pimpleback" Shell 8mm Faceted Coin Bead - 15-16 Inch Shape_Coin is desired by some collectorsA "pimpleback" is a freshwater mussel (Cyclonaias pustulosa) common in North American rivers, characterized by a thick, yellow brown to brown shell covered in bumps (pustules). While not typically purple, the inner lining (nacre) can be iridescent, and related species in the pimpleback complex are sometimes found in Texas waters.