Modeling the Viscoelastic Behavior of Quartz and Clay Minerals in Shale by Nanoindentation Creep Tests

Figure 2

Photomicrographs of quartz and clay minerals. The surface morphology of quartz and clay minerals is shown after (a–b) mechanical polishing and (c–f) ion polishing. Quartz is dark gray, translucent, contains small impurities, and has straight and sharp edges without a regular shape. The clay minerals are opaque and black after mechanical polishing, and located in pit areas as lumps or isolated grains along with organic matter. Magnifications: (a) and (c) 20× objective lens; (b) and (d) 50× objective lens; (e–f) 100× objective lens (the eyepiece magnification was 40× for all images).