In the past few days, the researcher ZhenYu He and his fellow researchers from Institute of Geology, Chinese Academy Of Geological Sciences, had a field trip in the Peak Yanhu of Yandangshan Global Geopark. The trip was mainly for the investigation into egg-like stones, which were caused by weathering of Quartz Syenite Porphyry. These stone eggs are primarily round or semi-round, with a diameter ranging from 1 to 10 meters. They are scattered around or overlapped with each other, contributing to a special view.

Egg-like stones are discovered in Quartz Syenite Porphyry, which stands for central intrusive facies of the caldera in Yandangshan, and is a symbol of the end to the volcanic activities in Yandangshan. These stones are primarily present in rocks with homogeneous features, and are widely discovered in granite-rich areas in the southeastern part of China. Joints in different directions and weathering in geological processes are important reasons for these stones, which are present on the ground one by one after water takes weathering product away.

Newly-discovered egg-like stones contribute to a new subject for scientific investigation, science popularization and tourist sightseeing.