Patent ID: 8664131

Claim:
A glass-ceramic comprising: a. a composition, in mole %, comprising: i. 62-75 SiO 2 ; ii. 10.5-17 Al 2 O 3 ; iii. 5-13 Li 3 O; iv. 0-4 ZnO; v. 0-8 MgO; vi. 2-5 TiO 2 ; vii. 0-4 B 2 O 3 ; viii. 0-5 Na 2 O; ix. 0-4 K 2 O; x. 0-2 ZrO 2 ; xi. 0-7 P 2 O 5 xii. 0-0.3 Fe 2 O 3 ; xiii. 0-2 MnOx; and xiv. 0.05-0.20 SnO 2 ; b. a ratio: [ Li 2 ⁢ O + Na 2 ⁢ O + K 2 ⁢ O + MgO + ZnO ] ⁢  [ Al 2 ⁢ O 3 + B 2 ⁢ O 3 ] between 0.7 to 1.5; c. a ratio: [ TiO 2 + SnO 2 ] ⁢ [ SiO 2 + B 2 ⁢ O 3 ] greater than about 0.04; d. one or more β-spodumene solid solutions comprising: i. at least about 70 wt % of the crystalline phases of the glass-ceramic and ii. one or more Li 3 O:Al 2 O 3 :SiO 2 ratios between about 1:1:4.5-1:1:8; e. at least one Ti-containing crystalline phase comprising: i. about 2.5-8 wt % of the crystalline phases of the glass-ceramic, ii. an acicular morphology exhibiting a length ≧about 20 nm, and iii. rutile; f. an opacity comprising ≧about 85% over the wavelength range of 400-700 nm for an about 0.8 mm thickness; and g. optionally, one or more crystalline phase comprising: i. up to about 10 wt % of the crystalline phases of the glass-ceramic; and ii. a spinel structure.