What is an Industrial Mineral?
An industrial mineral is any naturally-occurring rock or mineral of economic value, exclusive of metallic ores, mineral fuels, and gem stones. Industrial minerals may be located in igneous, metamorphic and sedimentary rocks (Bates and Jackson, 1984).
Industrial minerals that form from igneous processes include many pegmatite minerals, such as muscovite, feldspars, spodumene, tourmaline, and beryl, as well as the igneous rocks themselves. The latter, including granite, diorite, and gabbro, may be valued for their durability and beauty.
Industrial minerals that are formed as a result of metamorphism include the rocks slate and marble, as well as minerals asbestos, wollastonite, garnet, and talc.
Industrial minerals occur in marine sedimentary rocks (limestone, dolomite, salt, gypsum) and non-marine sedimentary rocks (sand & gravel in stream deposits).
Examples of all three types of industrial deposits can be seen in the Black Hills. For example if we were to drive on Highway 16 from Rapid City to Mount Rushmore, on the eastern side of the Black Hills , we would get a view of all three types of deposit in less then 25 miles. In Rapid City, we would find sedimentary deposits such as limestone and sand & gravel deposits, and as we travel southeast we would find gypsum (white rock) in the Spearfish Formation of the Red Valley. At Rockerville, we would eventually get to the metamorphic rocks made up of phyllite and schist. Around Keystone, and at Mt. Rushmore, we would find the igneous intrusion of the Harney Peak granite with its huge number (~10,000) of satellite pegmatites (very coarse-grained granitic rock).
Classifications of Industrial Minerals:
Industrial minerals can be subdivided into two basic groups based on uses:
Fertilizer and Chemical Minerals:
|These are minerals essential for growing food (mostly potassium, nitrogen, phosphorus) and in many chemical applications (e.g. salt, sulfur, boron, soda ash).|
|Such industrial minerals in the Black Hills area include spodumene, lepidolite, and fluorapatite.|
Construction and Manufacturing Minerals:
|These are minerals and rocks that are used extensively in our infrastructure, mostly in roads and buildings.|
|Most common in the Black Hills area are limestone (for cement and aggregate), gypsum, , common clay, bentonite, sand & gravel, slate and shale.|