Of glass-ceramics:

Kitchenware, non-glazed, greater than 75 percent by volume crystalline, of lithium aluminosilicate, having a linear coefficient of expansion not exceeding 10 x 10-7 per Kelvin within a temperature range of 0˚C to 300˚C, transparent, haze-free, exhibiting transmittances of infrared radiations in excess of 75 percent at a wavelength of 2.5 microns when measured on a sample 3 mm in thickness, and containing β-quartz solid solution as the predominant crystal phase

Other