Light blue lustrous fluorapatite crystal on a bit of calcite matrix, underside shows a second fluorapatite. The crystal has a nice termination on one end and the other end was contacted into the host rock. Blue is one of the more rare colours for apatite for the region.
During the Grenvillian orogeny these rocks had undergone intense deformation and intense metamorphism where calcitic marbles now dominate the lithology. Metasomatic reaction zones developed at the contacts of calcitic marbles and silicate rocks, causing remobilized carbonates with higher than usual quantities of fluorapatite to be injected into country rocks. Blue apatite or green is generally associated with calcite and the crystals are disseminated in clusters.*
*Géologie de la région du lac Sainte-Marie - Comté de Gatineau Cette étude s'est effectuée en coopération avec l'INRS-Géoressources. By Louise Langlais
Read the full report on the Lac Sainte-Marie area here (you may need to use google translate): https://gq.mines.gouv.qc.ca/documents/examine/MB9351/MB9351.pdf
