The present special publication addresses opportunities and challenges in meeting the demand for essential and critical metals and minerals needed to supply the green and sustainable societies of the future. The notion of criticality in different countries is discussed and examples of ongoing national and cross-country research and mapping programs are presented. In addition to the resource/reserve and technical-economic aspects, the social and environmental dimensions are also elaborated in some of the contributions, as holistic approaches to the exploration and exploitation of critical minerals and materials are needed to fulfill the green transition and goals for the Green Stone Age.