hyperaged

By directly comparing pristine amber samples (i.e. highly stabilized polymer glasses after aging for millions of years) to the same samples after being totally or partially rejuvenated, we have found that the two most prominent universal anomalous low-temperature properties of glasses, namely the tunnelling two-level systems and the so-called boson peak, persist essentially unchanged in both types of hyperaged geological glasses.

2015, Tomás Pérez-Castañeda, Rafael J. Jiménez-Riobóo, Miguel A. Ramos, “Do Two-Level Systems and Boson Peak persist or vanish in hyperaged geological glasses of amber?”, in arXiv