Dear colleagues and friends, We invite contributions to Goldschmidt 2021 in session *2h: C-O-H-N-S Volatiles and Mantle Processes: From Observation to Experiment.* https://2021.goldschmidt.info/goldschmidt/2021/meetingapp.cgi/Session/1884 Keynote speaker: Fabrizio Nestola Invited speakers: Maria Luce Frezzotti and Peter Barry The aim of this session is to discuss petrological, mineralogical, experimental, and interdisciplinary contributions that address the influence of C-O-H-N-S fluids in the mantle processes. Goldschmidt 2021 (4-9 July) will be a hybrid format, combining an onsite meeting in Lyon (France) and an online meeting. Important dates and deadlines are given below: *Important date:* February 12, 2021: Grant application deadline February 26, 2021: Abstract submission deadline and Student Helper application deadline May 18, 2021: Early registration deadline July 4 - 9: Goldschmidt2021 Conference in Lyon and online We look forward to your contribution! Best regards The conveners, Souvik Das, Renbiao Tao, Ananya Mallik, Lifei Zhang