Which mineral assemblage is representative of magmatic segregation deposits?

• A. Ores of Cu, Pb, Zn, Au, and Ag
• B. Carbonatites, chromite, pentlandite
• C. May be found at divergent, convergent and transform boundaries
• D. Nickel ore veins

Answer: (B)

Magmatic segregation deposits form as a magma cools and minerals crystallize at different densities, causing dense phases to settle and accumulate as ore-rich layers. In ultramafic to mafic magmas, this process concentrates chromite and nickel-bearing sulfide minerals like pentlandite, creating nickel- and chromite-rich ore bodies. Carbonatites are alkaline intrusions that can host such magmatic segregations, including pockets of chromite and nickel sulfide minerals. Thus, the mineral assemblage representative of magmatic segregation deposits includes carbonatites, chromite, and pentlandite. Other options point to ore types or settings more typical of hydrothermal, sedimentary, or tectonic contexts rather than the specific mineral assemblage produced by magmatic segregation.