Very high quality factor measured in annealed fused silica
  We present the results of quality factor measurements for rod samples made of fused silica. To decrease the dissipation we annealed our samples. The highest quality factor that we observed was $Q=(2.03\pm0.01)\times10^8$ for a mode at 384 Hz. This is the highest published value of $Q$ in fused silica measured to date. 
Alexandr Ageev, Belkis Cabrera Palmer, Antonio De Felice, Steven D.   Penn, Peter R. Saulson