Slate of finished and unfinished slate has increased. It has slate in various colors. Deposits of slate exist throughout the Australian continent, with large reserves quarried in the Adelaide Hills (Willunga and Kanmantoo) and the Mid North (Mintaro and Spalding). Because slate was formed in low heat and pressure, compared to a number of other metamorphic rocks, some fossils can be found in slate; sometimes even microscopic remains of delicate organisms can be found in slate. Slate Slate is a fine-grained, foliated, homogeneous metamorphic rock derived from an original shale-type sedimentary rock composed of clay or volcanic ash through low-grade regional
Slate industry in Spain product depends largely on the tectonic environment, the source of the sedimentary material, and the physical/chemical conditions prevalent during the sedimentation process. As the sedimentary deposits were compacted, water was squeezed out, hence turning clay minerals into mica, and then solid mudstone. The subsequent mountain building compaction which occurred over the next few million years resulted in an even stronger rearrangement and planar orientation of the minerals. This means that in true slate the cleavage plane is very different from the original bedding plane and led to the well developed cleavage for which the region is famous. The Galician slate