Patent ID: 7183232

Claim:
Translucent and radio-opaque glass ceramic which comprises Component Wt. % SiO 2 46.0–58.0 P 2 O 5 2.0–6.0 Me 2 O 3 10.0–22.0 Me 2 O 14.5–30.0 MeO 4.0–13.0 F 0.3–3.0, with Me 2 O 3 being selected from Component Wt. % Al 2 O 3 8.0–16.0 Y 2 O 3 0.1–9.0 B 2 O 3 0–9.0, Me 2 O being selected from Component Wt. % Li 2 O 0–3.0 Na 2 O 0–9.0 K 2 O 3.0–14.0 Rb 2 O 0–12.5 Cs 2 O 0–18.0, MeO being selected from Component Wt. % MgO 0–9.0 CaO 0–2.5 SrO 0–13.0 with the proviso that at least one of SrO or MgO≧3.1 wt. % if CaO is 0.1 to 2.5 wt.-%, and which has apatite as a main crystalline phase.