Well I’m finally writing again and this time about shale.
Shale is a smooth sedimentary rock made of mud that is a mix of clay minerals and tiny parts of other minerals such as quartz and calcite.
Although shale is usually gray it can also be: red, brown, green, and black. Minerals that make this rock more colorful are: hematite which makes it red, goethite which makes it brown, and chlorite, biotite or illite which make it green.
Shale is formed by the rock cycle. The particles that make shale can stay in water long after the larger particles of sand have formed into sediment. Shale is usually formed in very slow moving water and is usually found in lakes and rivers.