High-Grade Limestones in Austria
High-grade limestones are sedimentary or metamorphosed rocks (marbles) which consist mainly of calcite (rarely aragonite) and contain at least 75 % calcium carbonate.
While ordinary limestones are widely abundant, those qualifying for industrial minerals are much less common.
They must contain > 98 % calcium carbonate and display a purely white colour (> 90 % luminance). They were mostly deposited in environments far from land (e.g. reefs) or metamorphosed. As raw materials, they are used for many industrial processes and technical products.