A unique petrified tree fern from northeast china

A unique petrified tree fern displaying distinct patterns was recently discovered in northeast China, attracting considerable interest. This study provides a comprehensive set of data for this material obtained through standard gemological testing, petrographic observation, scanning electron microscopy, energy-dispersive spectroscopy, electron probe microanalysis, and Raman spectroscopy. The petrified tree fern exhibits colors ranging from golden yellow to brown, with additional variations caused by iron oxides. Chalcedony is the primary mineral component, while the presence of metastable moganite gives chalcedony its fibrous nature, contributing to the delicate structure of the samples. The surface pattern originates from plant structures preserved during silicification, further confirming the samples belong to the extinct Cretaceous period tree fern Tempskya sp.