@article{fdi:010086907,
  title = {{T}he '{S}tar of {D}avid' pattern and presence of macrosteps on ruby and sapphire crystals from {A}appaluttoq, {G}reenland},
  author = {{P}ignatelli, {I}. and {G}iuliani, {G}aston and {M}orlot, {C}. and {P}ardieu, {V}.},
  editor = {},
  language = {{ENG}},
  abstract = {{A} '{S}tar of {D}avid' appearance is rarely exhibited on gem corundum crystals due to triangular step patterns in opposing orientations on each pinacoidal face. {S}uch samples were recently found at the {A}appaluttoq mine in {G}reenland, and are characterised by eye-visible triangular macrosteps with micrometre- to millimetre-size edges, an uncommon feature on natural corundum crystals. {T}he edge height, as well as the presence of wide terraces and trench-like defects on the crystals, suggest that the macrosteps result from step bunching and faceting(1) processes. {T}he macrosteps likely formed under high-temperature conditions and intense fluid-rock interactions, in a growth medium where impurities and direction of fluid flow played an important role in the step formation. {L}arge macrosteps are also found on corundum crystals from other deposits of both magmatic and metamorphic origin.},
  keywords = {{GROENLAND}},
  booktitle = {},
  journal = {{J}ournal of {G}emmology},
  volume = {38},
  numero = {4},
  pages = {364--375},
  ISSN = {1355-4565},
  year = {2022},
  DOI = {10.15506/{J}o{G}.2022.38.4.364},
  URL = {https://www.documentation.ird.fr/hor/fdi:010086907},
}