Crystals (Apr 2024)

Ruby from Longido, Tanzania: Mining, Color, Inclusion, and Chemical Features

  • Yujie Gao,
  • Mingyue He,
  • Andrew Christopher Lucas,
  • Xueying Sun,
  • Dan Zhou,
  • Tiantian Huang,
  • Kai Li,
  • Darwin Fortaleché,
  • Moqing Lin,
  • Yuan Zhu,
  • Xiaoting Jin

DOI
https://doi.org/10.3390/cryst14040383
Journal volume & issue
Vol. 14, no. 4
p. 383

Abstract

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This article reports on the recent mining and production status of ruby in Longido, Tanzania. Faceted-grade rubies and their matrix from Longido Area, Tanzania, were investigated by standard gemological testing, including FTIR, UV-VIS, Raman spectra, and LA-ICP-MS. Microscopic observations revealed dense needle-like and triangular inclusions, distinct growth lines, and color banding as typical inclusions. In agreement with the Raman results, the transmission FTIR spectrum confirmed the presence of aluminum hydroxide. The Raman spectra identified associated minerals and inclusions, including zoisite, parasites, feldspar within the matrix, rutile, and diaspore in the ruby host. The chemistry analysis revealed a high amount of Cr and relatively low iron as a good indicator of geographic origin.

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