Works of "Research Collection"
Place Collected: Pashan Quarries
Place Collected: Zacatecas
Place Collected: Huayna Potosi Mine
Place Collected: Broken Hill
Place Collected: Onganja Mine
Place Collected: La Bufa Mine
Place Collected: Kirghese Steppes
Place Collected: Last Hope Mine
Place Collected: Panasqueira Mine, Algarve
Place Collected: Morro Velho Mine
Place Collected: Swan Lake