Siedel H, Rust M, Goth K, Krüger A, Heidenfelder W.  Rochlitz porphyry tuff (“Rochlitzer Porphyrtuff”): A candidate for “Global Heritage Stone Resource” designation from Germany.  Episodes 2019;42:81-91.  https://doi.org/10.18814/epiiugs/2019/019007