There are many variations on designs, colour, and composition, the last often attributed to the differences in mineral compositions of soil and rock used in the production of fritware.[1] The bodies of the fritware ceramics were always made quite thin to imitate their porcelain counterparts in China, a practice not common before the discovery of the frit technique which produced stronger ceramics.[2] In the 13th century the town of Kashan in Iran was an important centre for the production of fritware.[9] Abū'l-Qāsim, who came from a family of tilemakers in the city, wrote a treatise in 1301 on precious stones that included a chapter on the manufacture of fritware.[10] His recipe specified a fritware body containing a mixture of 10 parts silica to 1 part glass frit and 1 part clay.