Pegmatitic Rocks and Economic Geology

Abstract

AbstractThree minerals contribute to the built-up of Earth’s crust by almost ¾ and predominate in the group of industrial minerals. Feldspar is the top scorer with 56 vol.%; quartz is second most in abundance and accounts for 12 vol.% while phyllosilicates of the mica group are fifth among the top 10 with 4 vol.%. They are the major rock-forming constituents of the granite suite and the pegmatitic and aplitic rocks. Pegmatitic rocks similar in the gross mineralogical composition to granites but conspicuously different in size and quality of their minerals can deliver much better to the requirements of consumers from the industry using feldspar, quartz and mica as a raw material. In addition, these rocks may contain specific elements present in quantity so that they attain even ore grade as it is the case with Nb, Ta, Li, Mo, Sn, W, Be, Sc, Cs, Rb, REE, Y and U or they are targeted upon for their gemstones such as B, Be and Li. Although operated mainly for their quartz and feldspar contents, some of these rocks in Central Europe are also strongly enriched in rare elements such as Li, Nb, Ta, Be, REE and U and therefore have not only attracted the attention of mining engineers interested in industrial minerals but also encouraged mineralogists to investigate the wealth of minerals, with much success. The Hagendorf-Pleystein mining district consists of several pegmatites and aplites, including the largest pegmatite stock in Central Europe at Hagendorf-South, with more than 200 minerals. In the “Chessboard classification scheme of mineral deposits” (Dill, Earth Sci Rev 100:1–420, 2010) the outstanding economic importance of pegmatitic and aplitic rocks, particularly for future technologies is on a world-wide scale in context with other mineral deposits hosted by magmatic and metamorphic rocks. Several attempts have been made to squeeze pegmatites into classification schemes, yet with different success. A classification scheme should cater for the extractive and genetic part of economic geology alike. A new classification scheme, which is based on the Chemical composition, the Mineral assemblage and the Structural geology of pegmatitic rocks and for which the acronym CMS has been coined is put forward as “CMS classification scheme of pegmatitic and aplitic rocks” (Dill, Ore Geol Rev 69, 2015). It can be used in a short and long version and has two major columns the ore body and ore composition, it can be correlated with the “Chessboard classification scheme of mineral deposits”, and as such open for amendments and applicable also in a digital way. The extractive geology of various types of pegmatitic and rocks is depicted from the past until today.KeywordsClassification SchemeMining OperationMining DistrictBohemian MassifOpencast MiningThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.