Tesaurus d'Art i Arquitectura Getty Institute 0000-00-00 2024-01-24 15:40:44 en touchstone300011149basaniteLydian stonestone, Lydian A velvety-black variety of cryptocrystalline quartz, siliceous shale, or similar substance used by jewelers for testing the purity of precious metal, especially gold, by the streak left on the stone when rubbed with the metal. pedra de toc piedra de toque 2026-03-30 20:50:50