a porcelain composition for dental restorations comprising a leucite crystallite phase and a glass matrix phase , wherein the leucite crystallites possess diameters not exceeding about 10 micron . preferably , the porcelain composition has a maturing temperature from about 750 ° to about 1050 ° c . and a coefficient of thermal expansion from about 12 × 10 − 6 /° c . to about 17 . 5 × 10 − 6 /° c ., and comprises : component amount sio 2 57 - 66 al 2 o 3 7 - 15 k 2 o 7 - 15 na 2 o 7 - 12 li 2 o 0 . 5 - 3 .