This data has refractive index (RI) measurements for 30 fragments on each of the five strata - float surface (FS), near float surface (NFS), bulk (B), near anti-float (NAFS), and anti-float (AFS).
data(newton.df)A. W. N. Newton, J. M. Curran, C. M. Triggs, and J. S. Buckleton. The consequences of potentially differing distributions of the refractive indices of glass fragments from control and recovered sources. Forensic Science International, 140(2?3):185-193, March 2004.