RARE Vintage Corning Ware 1960 – 1970 La Marjolaine Spice Of Life Gorgeous?? 7 x 5 1/2 x 3 (p-4-b). Condition: Good – In very good vintage condition. Marked: Corning Ware, Made in USA. Marked: Pyrex on the top of the Lid. Donald Stookey of the Corning Research and Development Division discovered Pyroceram, a white glass-ceramic material capable of withstanding a thermal shock of up to 450 K (840 °F), by accident. He was working with photosensitive glass and placed a piece into a furnace planning on heating it to 600 degrees Fahrenheit. When he checked on his sample, the furnace was at 900 degrees and the glass had turned milky white. He reached into the furnace with tongs to discard the sample, and it slipped and hit the floor without shattering. Pyroceram was originally used in the ballistic missile program as a heat-resistant material for nose cones. Glass-ceramics are polycrystalline materials produced through controlled crystallization of base glass, producing a fine uniform dispersion of crystals throughout the bulk material. Crystallization is accomplished by subjecting suitable glasses to a carefully regulated heat treatment schedule, resulting in the nucleation and growth of crystal phases. Pyroceram is the original glass-ceramic material developed and trademarked by Corning Glass in the 1950s. Pyroceram is an opaque, white, glass material, commonly used in kitchenware, glass stove tops, wood stove doors, etc.. It has high heat tolerance and low thermal expansion.