All metals are sourced from ores, and all ores contain impurities. For metal producers, unwanted minerals are an inherent part of the production process and impurities must be removed prior to the metal reaching its final form.
The simplest method of removing impurities from metallic ores is with the addition of a metallurgical flux during the smelting stage of metals production. The primary purpose of a flux is to react and combine with unwanted minerals in the metallic melt to form a slag that can be separated from the metal and removed from the furnace.
Fluxes are a key component of the metals production process and without them metallic products could not exist; yet few minerals meet the demanding criteria of this market. Considering their importance in metals production, it is somewhat ironic that flux minerals are considered to be a niche market by many industrial minerals producers.