@article{PAR00025119,
  title = {{C}olombian emerald oddities : review and formation mechanisms},
  author = {{P}ignatelli, {I}. and {G}iuliani, {G}aston and {M}orlot, {C}. and {S}alsi, {L}. and {M}artayan, {G}.},
  editor = {},
  language = {{ENG}},
  abstract = {{E}xceptional mineralogical oddities of gemmological interest have been found in {C}olombia's emerald deposits. {T}heir particular sedimentary-hydrothermal geological environment is characterised by large fluid circulations and changes in thermodynamic conditions during emerald precipitation. {I}n this context, various etching processes and growth perturbations affected the crystals in both the eastern and western belts of these emerald deposits. {I}n the eastern belt, variations in post-growth etching are responsible for the formation of 'vaso' (cup), 'spongy' and spear-shaped emeralds, and etching associated with near-parallel growth of elongated crystals resulted in fibrous emerald specimens. {I}n addition, rare sceptre emeralds formed by epitaxial lateral overgrowth due to the arrival of a later mineralising pulse in the hydrothermal system. '{E}merald gastropods' are also found in the eastern belt, and formed by the replacement of fossil aragonite by calcite which later dissolved away and was replaced by emerald. {I}n the western emerald belt, hydrothermal fluid circulation sometimes resulted in non-uniform crystal growth, giving rise to horseshoe-shaped meralds characterised by an incomplete hexagonal prismatic habit. {A}n unusual sample of a calcitised trapiche emerald-due to fluid circulation affecting trapiche emerald-bearing black shale-is also described.},
  keywords = {{COLOMBIE}},
  booktitle = {},
  journal = {{J}ournal of {G}emmology},
  volume = {38},
  numero = {1},
  pages = {26--43},
  ISSN = {1355-4565},
  year = {2022},
  DOI = {10.15506/{J}o{G}.2022.38.1.26},
  URL = {https://www.documentation.ird.fr/hor/{PAR}00025119},
}