| CPC C03C 10/0009 (2013.01) [C03C 3/062 (2013.01); C03C 23/008 (2013.01); C03C 23/009 (2013.01); C03C 2203/52 (2013.01)] | 26 Claims |

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1. A glass glass-ceramic composite comprising:
a substrate comprising: an alkali containing glass bulk, the glass bulk comprising material comprising: Al2O3 and SiO2 and alkali, and
a glass-ceramic surface layer integral to the glass substrate produced from the alkali containing glass bulk material of the substrate, by reducing the concentration of alkali in the surface layer of the substrate,
the surface layer of the substrate comprising an alkali-depleted glass ceramic comprising Al2O3 and SiO2 with at least 5% crystalline phase by volume, wherein the alkali-depleted glass ceramic surface layer comprises a mol % Al2O3 of at least 51%.
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