• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Brazilian Journal of Geology >Textural patterns, mineralogy, and chemistry of sandstone-related Cal?§adinha chalcedony (Piau?-, Brazil)
【24h】

Textural patterns, mineralogy, and chemistry of sandstone-related Cal?§adinha chalcedony (Piau?-, Brazil)

机译：与砂岩有关的Cal？§adinha玉髓（Piau？-，巴西）的质地模式，矿物学和化学性质

获取原文
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Paleozoic sandstones of the Parna?-ba Basin, in addition to hosting opal deposits, also have occurrences of chalcedonies with potential for mineral and ornamental handicrafts, in addition to assisting the understanding of the geological evolution of the basin. However, the chalcedonies were not investigated yet, and this study intended to fulfill this gap by the investigation of the chalcedonies of Cal?§adinha in Piau?-. Fieldwork, microtexturals analysis, X-ray diffraction and scanning electron microscopy with energy dispersive spectrometry, chemical analysis, and gemological assessments were developed. Four distinct types of chalcedonies have been distinguished. They stand out for their well distribution of Fe and Mn dendrites, which involves opal nodules, and contains microcavities with well-formed microcrystalline quartz, nontronite, and palygorskite. The mesoscopic features of these chalcedonies and cabochon and free forms cutting show potential for use in mineral crafts and semi-jewels. As expected, the chalcedonies are dominated by high contents of SiO 2 , besides the low and variable contents of Al 2 O 3 , Fe 2 O 3 , MgO, and TiO 2 . Among trace elements that show high Ba contents, bound in barite, seem also to be a geochemical signature of the country sandstones in Parna?-ba basin. These chalcedonies were formed during the partial solubilization of SiO 2 of sandstones, which was promoted during their tectonic formation in faults and fractures zones.
机译：帕纳巴盆地的古生代砂岩除了可以容纳蛋白石沉积外，还可以发现玉髓，可能有助于矿物和装饰性手工艺品，此外还有助于了解该盆地的地质演化。但是，尚未对玉髓进行研究，本研究旨在通过对Piau？-Cal？adinha玉髓的研究来填补这一空白。开展了野外工作，微观结构分析，X射线衍射和带能谱仪，化学分析和宝石学评估的扫描电子显微镜。区别了四种不同的玉髓。它们因其铁和锰树枝状晶体分布良好而突出，这些树枝状晶体涉及蛋白石结节，并且包含微腔，这些微腔具有形成良好的微晶石英，绿脱石和坡缕石。这些玉髓和凸圆形宝石的介观特征以及自由形式的切割显示出可用于矿物工艺品和半宝石的潜力。不出所料，除了Al 2 O 3，Fe 2 O 3，MgO和TiO 2的含量低而可变之外，玉髓中还以高含量的SiO 2为主。在重晶石中显示出高Ba含量的微量元素中，似乎也是Parna？-ba盆地的乡村砂岩的地球化学特征。这些玉髓是在砂岩的SiO 2部分溶解的过程中形成的，而在断裂和断裂带的构造构造过程中，这种作用得到了促进。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号