Anorthosite-hosted igneous phosphate ore satisfies future demands for high-quality phosphate (apatite) for green technologies, such as lithium ferro phosphate (LFP) batteries. The newly discovered Bégin-Lamarche Fe-Ti-P deposit in the central Grenville Province, Canada, is hosted in the Proterozoic Lac-Saint-Jean Anorthositic Suite (∼1157 to 1142 Ma) – one of the world’s largest anorthosite massifs. The deposit extends ∼2.5 km along a NNE-SSW axis with a thickness of ∼200 to 400 m. The deposit contains multiple layers of oxide-apatite ultramafic (OAUM) and oxide-apatite mafic (OAM) mineralization, with some parts reaching unusually high amounts of fluorapatite (up to 86 vol%). The OAUM rocks commonly contain a higher amount of fluorapatite (18–86 %) than that of the OAM rocks (up to 26 %). Both OAUM (∼0 % plagioclase) and OAM (∼4–69 ‰ plagioclase) rocks contain variable amounts of olivine, orthopyroxene, amphibole, biotite, ilmenite, and magnetite. The positive correlations between the Cl as well as REE + Y contents in fluorapatite and the Mg# of coexisting orthopyroxene indicate that fluorapatite with low Cl and REE + Y contents crystallized during the late stages of magma crystallization. A high amount of fluorapatite crystallization during the initial stages of magma crystallization decreased the Cl and REE + Y concentrations of the late-stage magma. Therefore, the Mg# of orthopyroxene provides an exploration tool for targeting the desirable low Cl-phosphate ore in this type of deposit. Furthermore, low Al2O3 contents (0.88–2.47 wt%) of orthopyroxene from the mineralized rocks of the deposit indicate that the magma crystallized at mid-low crustal levels (≤3.1 kbar, i.e., ≤11.7 km). The early crystallizing OAUM rocks (∼0 % plagioclase) with high fluorapatite contents (18–86 %) indicate that the absence of plagioclase among the crystallizing phases helped maintain a high calcium (Ca) content in the magma. The high Ca content ultimately kept the required P2O5 content low enough for apatite saturation, which facilitated apatite crystallization for a longer duration, with a high volume at the initial stages of crystallization. Similar to other anorthosite (or mafic rock)-hosted phosphate deposits of the Grenville Province, the deposit represents a high-quality, environmentally friendly phosphate ore with a low amount of sulfide minerals (<1 vol%), Pb (≤11 ppm), Th (≤2 ppm), and U (≤2 ppm).
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