In this perspective article, we illustrate the importance and versatility of the Coulomb criterion that serves as a bridge between the fields of powder technology and rock mechanics/geomechanics. We first describe the essence of the Coulomb criterion and its physical meaning, revealing surprising similarities regarding its applications between both fields. We then discuss the rock mechanics applications and limitations at two extreme scales, the Earth's crust (tens of kilometers) and intact rocks (meters). We finally offer thoughts on bridging these scales. The context of the article is essential not only to the rock mechanics/geomechanics community but also to a broader powder technology community. (C) 2020 Elsevier B.V. All rights reserved.