Notable geological associations include mineral occurrences hosted in a compositionally wide variety of igneous rocks including granitic and syenitic pegmatites, anorthosite and related anorogenic plutonic rocks, carbonatites, and iron-oxide–apatite (IOA) deposits. Numerous localities are also hosted in, or influenced by, metasedimentary rocks. Of particular significance are the extensive marble and calc-silicate gneisses of the Grenville Supergroup, including associated skarns and enigmatic calcite vein-dikes. In addition, minerals related to granulite-facies metamorphism, hydrothermal alteration, supergene mineralization, and weathering occur in many diverse Grenville lithologies and/or crosscut them.