Fluorapatite from Pegmatites of the Oxford Pegmatite Field, Maine—Chemistry, Color and Morphology

Apatite is widespread in pegmatites in the Oxford Pegmatite Field and is dominantly fluorapatite. Hydroxylapatite does occur but is rare. Carbonate-rich fluorapatite occurs as a partial replacement of beryllonite. True chlorapatite does not occur, but some fluorapatites contain a small amount of chloride. Apatite occurs throughout the pegmatites, both in the massive pegmatite as grains and as well-formed crystals in primary and secondary miarolitic cavities and in small interstitial voids. A correlation between color, crystal forms and composition, mainly with respect to Mn and Fe, has been observed. We focused on apatite in miarolitic cavities in these pegmatites and, notably, the well-studied Emmons pegmatite. The goal of the study was to demonstrate that a relationship exists among composition, color and morphology.