@article{fdi:010066282,
  title = {{C}olombian trapiche emeralds : recent advances in understanding their formation},
  author = {{P}ignatelli, {I}. and {G}iuliani, {G}aston and {O}hnenstetter, {D}. and {A}grosi, {G}. and {M}athieu, {S}. and {M}orlot, {C}. and {B}ranquet, {Y}.},
  editor = {},
  language = {{ENG}},
  abstract = {{C}olombia is the traditional source of the world's finest emeralds, including the famed trapiche crystals, with their distinctive texture resembling a wheel with six spokes, {T}his gemological curiosity, found exclusively in the black shales of the country's western emerald zone, is linked to the peculiar structural geology of the deposits. {T}he study presents a review and update on {C}olombian trapiche emeralds, followed by a three-dimensional examination of the crystals combined with spectroscopic and chemical analyses. {T}he proposed formation model incorporates the structural geology of the deposits with the formation of trapiche and non-trapiche emeralds, {T}he fluid accumulation at the faults' tip in the black shales leads to maximum fluid overpressure and sudden decompression and formation of the emerald bearing vein system. {T}he authors show that trapiche emerald growth starts at the beginning of the decompression that is responsible for local supersaturation of the fluid. {T}he hydrothermal fluid comes in contact with the black shale matrix, favoring the formation of emerald seed crystals. {D}uring the growth of these seeds, textural sector zoning occurs, sometimes associated with chemical sector zoning, along with displacement of the matrix. {D}isplacement growth occurs because the emeralds continue their growth, pushing the matrix material away from the growing faces. {A}n overgrowth, generally of gem quality, can form after decompression, surrounding the core, the arms, and the dendrites, restoring the emeralds' euhedral habit.},
  keywords = {{COLOMBIE}},
  booktitle = {},
  journal = {{G}ems and {G}emology},
  volume = {51},
  numero = {3},
  pages = {222--259},
  ISSN = {0016-626{X}},
  year = {2015},
  DOI = {10.5741/gems.51.3.222},
  URL = {https://www.documentation.ird.fr/hor/fdi:010066282},
}