Medical Definition of amnesia. 1: loss of memory sometimes including the memory of personal identity due to brain injury, shock, fatigue, repression, or illness or sometimes induced by anesthesia a period of amnesia after the wreck.
Shale is a fine-grained sedimentary rock that forms from the compaction of silt and clay-size mineral particles that we commonly call mud. This composition places shale in a category of sedimentary rocks known as mudstones.
All rocks can become other rocks by the processes of erosion  and metamorphism.    An igneous rock may become eroded into its constituent mineral  grains such as â¦ quartz and feldspar, which are transported by wind  and water, eventually settling to form a sedimentary rock.There are 4 main groups that igneous rock is divided into by  chemical content. These are felsic, intermediate, mafic and  ultramafic. Felsic rocks are those that are rich in silica content  and low in iron and magnesium. Examples include obsidian, granite  and rhyolite.