SciELO - Brasil - Orange opals from Buriti dos Montes, Piauí: solid inclusions as genetic guides Orange opals from Buriti dos Montes, Piauí: solid inclusions as genetic guides

In the Piauí State of northeastern Brazil, Pedro II and Buriti dos Montes counties have the most important opal occurrences of the country. The gemological qualities of these opals are equivalent to the famous Australian opals. According to Gomes (2002)GOMES, E. R. Mineralogia e gemologia da opala laranja de Buriti dos Montes (Piauí, Brasil). Belém: Centro de Geociências, Universidade Federal do Pará, 2002. 89p. (Dissertação de Mestrado)., the orange opals from Buriti dos Montes do not exert the same fascination as the precious opals from Pedro II because they do not show a play-of-colors. However, this variety has been highly appreciated due to other features, which are also suitable for use in jewelry, such as their orange hues, transparency, hardness and relatively high stability. The exotic content of solid inclusions provides greater beauty to the orange opals found in this region. These inclusions occur isolated or in various arrangements with millimetric to centimetric si