Uncovered by renowned British Egyptologist Brian Walter Emery while excavating the tomb of Prince Sabu, son of Adjuib Pharaoh, governor of the First Dynasty (circa 3000 BCE), the Schist Disk was found among some common funerary objects (including stone vessels, flint knives, arrows, and a few copper tools) Emery initially cataloged as “a container in the form of a schist bowl.”
The term schist, derived from the Greek word σχ?ζειν meaning “to split” (referring to the relative ease with which this material can be split along the lateral plane), is a category of medium-grade metamorphic rock rich in what are termed “lamellar” minerals, which include mica, chlorite, talc, hornblende, and graphite.
Derived from clay and mud, which have undergone a series of extreme physical-chemical (transitioning from shale to slate to phyllite), most schists are made of mica, but graphite and chlorite are also quite common.
And while the existence of ancient objects made of this hard but brittle material is far from rare, the design and craftsmanship of this disk, in particular, is astounding—if not more than a little eerie.
Not only did it require extraordinary practice and patience to create, but other similarly-crafted pieces also have never been found. 1/ 
