Platinum Group Metals (PGMs)—platinum, palladium, rhodium, ruthenium, iridium, and osmium—share similar chemical and physical characteristics. These metals are exceptionally rare, with annual global production amounting to only a few hundred tonnes. Platinum’s unique properties, such as its high melting point and resistance to corrosion, make it highly valued in numerous industrial applications. Africa contains the majority of the world’s known reserves, establishing it as the primary source for global supply.
The Bushveld Igneous Complex: Platinum’s Geological Home
The vast majority of African platinum deposits are concentrated within a unique geological structure known as the Bushveld Igneous Complex (BIC). This colossal layered mafic intrusion, located in South Africa, is estimated to be approximately two billion years old. The formation of the BIC involved repeated intrusions of magma into the Earth’s crust, which then cooled and crystallized slowly over time. This process led to the segregation of minerals into distinct, near-horizontal layers.
The layering within the BIC created several zones that are unusually rich in PGMs, commonly referred to as “reefs.” The two most significant of these layers are the Merensky Reef and the UG2 Chromitite Reef. The Merensky Reef is a narrow, sulfide-rich layer of pyroxenite, often less than a meter thick, which hosts a high concentration of PGMs, along with copper and nickel by-products. The UG2 Chromitite Reef is a chromite-rich layer situated below the Merensky Reef, and it contains one of the planet’s largest resources of Platinum Group Elements. A third significant layer, the Platreef, is found in the northern part of the complex.
South Africa: The Global Platinum Hub
South Africa’s position as the world’s leading platinum producer is directly linked to the extent of the Bushveld Igneous Complex within its borders. The BIC’s surface exposure is divided into four main lobes—the western, eastern, northern, and southern limbs—which span across four provinces. The nation’s reserves represent the largest known PGM resource globally, supplying a large percentage of the world’s annual production.
Platinum mining operations are primarily focused on the western and eastern limbs of the BIC. The North West Province contains the western limb, where the historic mining center of Rustenburg is located. The Rustenburg area has been a major hub for platinum mining since the deposits were first discovered in the 1920s. Mining began here with the Merensky Reef, a narrow layer that requires deep, labor-intensive underground operations.
The eastern limb of the complex extends into the Mpumalanga and Limpopo provinces. The Limpopo Province hosts the northernmost extension of the complex, which includes the Platreef deposit near the town of Mokopane. The geographic scale of the BIC, combined with the thickness and grade of the Merensky and UG2 reefs, allows South Africa to dominate the global platinum market.
Key Secondary African Producers
Beyond South Africa, the second-largest source of platinum group metals in Africa is the neighboring nation of Zimbabwe. The PGM reserves here are contained within a distinct geological formation known as the Great Dyke. This linear feature extends for approximately 550 kilometers across the center of the country and is a massive group of layered ultramafic intrusions.
Unlike the BIC, the Great Dyke’s economically viable mineralization is concentrated in a single horizon called the Main Sulphide Zone (MSZ). The MSZ is a relatively thin layer that occurs within the uppermost pyroxenite rock unit of the intrusion. The concentration of PGMs in this zone is high enough to support several active mining operations. Mines such as Ngezi, Unki, and Mimosa extract ore from this zone, making Zimbabwe a significant contributor to the world’s platinum supply. The Great Dyke represents the world’s second-largest PGM resource.