Industrial minerals (except quartz) used as basic mold material with standard foundry binders for the production of cores and molds. Special sands are natural mineral sands, sintering and melting products (Diagram 1), which are produced in grainy form or transferred to grainy form by breaking, grading and screening processes or mineral sands derived from other physiochemical processes. Special sands are particularly distinguished from quartz sand by their considerably reduced thermal expansion behavior in a temperature range of 20 to 800°C and by additional specific physiochemical properties like cooling, isolation, spherical grains, low bulk density and low chemical affinity (Fig.1, Diagram 2). Additionally, they feature a higher (heavy minerals) or lower (aluminum silicates) thermal conductivity than quartz sand. Fig. 2 illustrates quartz sand in comparison to the selected examples of special sands illustrated in the figures 3 to 13, provided by Mr. Dipl.-Min. Ulrich Recknagel, Hüttenes-Albertus Chemische Werke GmbH, Düsseldorf.