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Indonesia | |
| [var. Precious Opal] Sun, T. T., Mok, P. C., Paul, S. L., Paramita, M., Arps, C. E., Atichat, W., ... & Wijaya, K. (2008). Precious Opal from Java (Gemmological properties, micro-and nano-structures) Date: 10-05-2008. Extra Lapis - English No. 10 Opal |
| Lowenstern, J. B., van Hinsberg, V., Berlo, K., Liesegang, M., Iacovino, K., Bindeman, I. N., & Wright, H. M. (2018). Opal-A in glassy pumice, acid alteration, and the 1817 phreatomagmatic eruption at Kawah Ijen (Java), Indonesia. Frontiers in Earth Science, 6, 11. |
| Sujatmiko, Dr H. C. Einfalt, Dr U. Henn (2007) Opal from Java, Indonesia and Its Varieties. http://www.hagi.or.id/paper/opal-from-java-indonesia-and-its-varieties/ |
| [var. Opal-CT] Mazot, A., Bernard, A., Sutawidjaja, I.S. (2007) Hydrothermal system of the Papandayan Volcano, West Java, Indonesia and its geochemistry evolution of thermal water after the November 2002 eruption. Jurnal Geologi Indonesia, 2:1, 15-29. |
Java, Indonesia