ceramics is clay which is dirt's from earth that have been purified meaning the rocks twigs etc have been taken out. afterwards water is added making the clay consistency.
Ceramic vases are made from Clay. However it depends on the purpose and the choice of the potter making the vase some of them can be made out of glass, That's to say Silica. Because they are Ceramic...
Ceramic is not a material/noun, but rather an adjective used to identify something as being made of clay. So, many things can be ceramic, including plates, vases, boxes, and sculptures.