Apatite

Apatite frequently appears as an accessory mineral in igneous and metamorphic rocks, serving as the most prevalent phosphate mineral. Typically, its presence is in the form of small grains, often discernible only in thin sections.

Larger, well-defined apatite crystals are typically confined to pegmatites, gneiss originating from sediment-enriched carbonate minerals, skarns, or marble. Additionally, apatite can be identified in clastic sedimentary rocks as grains eroded from the source rock.