Opal from selected localities.
Germany | |
| [Opal-A var: Opal-AN] F. Müller: "Bayerns steinreiche Ecke", 2nd ed., Oberfränkische Verlagsanstalt und Druckerei GmbH (Hof), 1984 |
| [Opal-A var: Opal-AN] Rost, F. (1949): Contributions to Mineralogy and Petrology 1(5/6), 627-688. |