The Société internationale forestière et minière du Congo (French;), known as Forminière, was a mining company in the Belgian Congo (modern-day Democratic Republic of the Congo). Founded by the industrialist Jean Jadot in 1906, the company began diamond mining in Kasai in 1913. At its height, Forminière was involved in gold and silver mining, cotton, palm and rubber cultivation, farming, sawmilling and even owned shops. The Belgian colonial state co-owned 50 percent of the company's capital, the rest being held largely by American shareholders.
The company was founded in 1906 under the Congo Free State, controlled personally by Leopold II of Belgium. It was founded contemporaneously with the Union Minière du Haut-Katanga and the Compagnie de Chemin de fer du Katanga. A minority stake was sold to American Congo Company both with the aim of reducing growing criticism of the Congo Free State, and also in the hope that foreign forces would intervene to protect his commercial interests.[1] Unlike the Union Minière du Haut-Katanga, the mineral resources of the Forminière concession were unknown, and initial exploration focused on gold prospecting. After diamonds were discovered, serious diamond mining began in 1913.
For the length of its existence, from 1913 to 1961, Forminière had a monopoly on diamond production in Kasai.[2]
Due in part to a drop in production that coincided with the outbreak of the Second World War, the United States' Office of Strategic Services to investigate possible diversion of production to the Axis powers. In a 1945 lawsuit against De Beers, the United States Department of Justice Antitrust Division attempted to get access to purchasing directly from Forminière instead of through the De Beers as a middleman.[3] The lawsuit was eventually dropped in 1948 due to jurisdictional issues.[4]
Forminière and its rival, the Société minière de Beceka (Mibeka), later changed to "de Bakwanga" (MIBA), dominated the production of diamonds in the Belgian Congo. In 1959, Forminière's production of diamonds rose to 425,234 carats.[5] However, after the 1960 independence of Congo and unrest in the region, company operations soon ceased.[2] Forminière was the principal corporate supporter of the secessionist state of South Kasai and received concessions from its government in exchange for financial support.