Firing process with porcelain is comparable to any mid-range or high-fire stoneware body. Porcelain is defined by type of clay in its composition, which can be highly variable. The clay mineral kaolinite is often a significant component. Other materials can include feldspar, ball clay, glass, bone ash, and quartz. Many porcelain bodies are being developed to fully vitrify at mid range and even low-fire temperatures. This allows for broader glaze effects and firing styles.