Counting function for a sphere of anisotropic quartz
  We calculate the leading Weyl term of the counting function for a mono-crystalline quartz sphere. In contrast to other studies of counting functions, the anisotropy of quartz is a crucial element in our investigation. Hence, we do not obtain a simple analytical form, but we carry out a numerical evaluation. To this end we employ the Radon transform representation of the Green's function. We compare our result to a previously measured unique data set of several tens of thousands of resonances. 
N. Sondergaard, T. Guhr, M. Oxborrow, K. Schaadt and C. Ellegaard