Ores and the process of metamorphism share “cause” and “effect” relationships. Metamorphism can be the cause behind formation of ore deposits. For example, non-metallic ore deposits of kyanite, sillimanite, and graphite are formed by regional metamorphism of silicate rocks. These ores owe their origin to the direct consequence of metamorphism, i.e., by metamorphic reactions, such as the formation of graphite from kerogen or kyanite from aluminous clay minerals. Metamorphism can also be the indirect cause behind ore deposit formation. For example, large amount of fluid can be generated by prograde metamorphic devolatilization reactions. Under suitable geological conditions, these fluids can become ore-forming, as in the case of Archean gold-quartz lode type deposits (Chap. 1 , Table 1.3 ). This chapter deals with the effects of metamorphism on already formed hydrothermal ore deposits. Several authors (Vokes, 1969, 2000; Stanton, 1972; Mookherjee, 1976; Craig & Vokes, 1993; Vokes & Craig, 1993) have stressed the importance for the identification of the features pertinent to metamorphism of sulfide ore deposits and for establishing their evolutionary history. For that purpose, remobilization is one of the important aspects to describe the evolutionary stages of ore deposits. It controls the geometry and distribution (grade, tonnage) of the ore minerals, in any metamorphosed ore body.