@article{fdi:010070895,
  title = {{R}ecent advances in understanding the similarities and differences of colombian euclases},
  author = {{P}ignatelli, {I}. and {G}iuliani, {G}aston and {M}orlot, {C}. and {R}ouer, {O}. and {C}laiser, {N}. and {C}hatagnier, {P}. {Y}. and {G}oubert, {D}.},
  editor = {},
  language = {{ENG}},
  abstract = {{C}olombian euclase is rare and associated with emerald in medium-temperature hydrothermal veins hosted by {L}ower {C}retaceous black shales ({BS}). {T}he original sources of euclase production were the mining districts of {G}achala and {C}hivor in the eastern emerald belt, but in 2016 euclases were also found at the {L}a {M}arina mine in the western emerald belt. {T}he present study is centered on a chemical and mineralogical examination of zoned {C}olombian euclase sold on the gem market as "trapiche'. {I}ts texture is characterized by growth bands and sectors distinguished by the presence of numerous inclusions (mainly pyrite, carbonates, and organic matter) which represent around 0.2% of the total volume of the crystals. {X}ray computed tomography showed that the largest inclusions are randomly located, whereas the small inclusions are concentrated in the center of the crystals, along the crystallographic b axis, between neighboring growth sectors and between growth bands in each sector. {T}he texture cannot be defined as "trapiche', like that of {C}olombian emeralds, because there is no matrix material from the surrounding {BS} trapped between the growth sectors and accumulated as dendrites. {T}hree-phase fluid inclusions ({FI}) containing halite, liquid, and vapor phases are also observed in the euclase, and their volume is identical to that of the inclusions in emerald. {C}hromium and vanadium are the main chromophores, and the highest concentrations (1240 and 400 ppm, respectively) were found in deep blue-colored zones. {S}urprisingly, the euclase crystals have high {G}e contents, between 230 and 530 ppm. {T}he {R}are {E}arth {E}lement ({REE}) patterns of euclase are inherited from the enclosed {BS} or albitized and carbonatized {BS}. {E}uclase has the same {REE} pattern as emerald from the {G}achala mines with an {E}u anomaly ({E}u/{E}u* similar to 0.40) and a depletion in {H}eavy {R}are {E}arth {E}lements ({HREE}). {T}he present study allows for the reconstruction of the formation conditions of "trapiche' euclase and discussion about its probable geographic origin, i.e., the eastern emerald belt.},
  keywords = {{C}olombia ; emerald belts ; euclase ; "trapiche' texture ; trace-elements ; {REE} ; germanium ; geological formation ; {COLOMBIE}},
  booktitle = {},
  journal = {{C}anadian {M}ineralogist},
  volume = {55},
  numero = {4},
  pages = {799--820},
  ISSN = {0008-4476},
  year = {2017},
  DOI = {10.3749/canmin.1700011},
  URL = {https://www.documentation.ird.fr/hor/fdi:010070895},
}