Gemmy red proustite crystal (1 mm tall) from Dolyhir Quarry, Old Radnor. Proustite is one of the rarer Welsh species and highly sought-after by collectors. © D.I. Green. Crisial gemog coch o'r mwyn proustit (1 mm o hyd) o Chwarel Dôl-hir, Pencraig, Maesyfed. Mae proustit yn un o fwynau prinnaf Cymru ac mae galw mawr amdano ymhlith casglwyr. © D.I. Green. For more information, see the Museums online crystal gallery