Fig. 9From: Geoenvironmental investigation of Sahure’s pyramid, Abusir archeological site, Giza, Egypta Thin section for the core stone investigated under the polarizing microscope. The sample shows the pore spaces, channels (microcracks), and dolomite presented as alteration minerals after calcite (dolomitization process). b The casing stone under a polarizing microscope. The stone is cut by microveinlets filled with secondary calcite and traces of quartz. Quartz presents as a secondary replacement mineral over carbonates, especially microfossils. c The decayed casing stone under a polarizing microscope. Secondary quartz replaces calcite both in the matrix and in some microfossils. Secondary gypsum replaces calcite and partially fills cavities and pore spaces. d Observed stone fragments are of sedimentary (fossiliferous limestone, gypsum (chemical alteration byproduct), feldspathic graywacke, and ironstone) and igneous (porphyritic basalt and rhyolite) origin e in basaltic mortar. Gypsum rock fragments are composed of a network of very fine-grained irregular gypsum crystals, and this texture is characteristic of secondary gypsum after anhydrite. f Some grains of quartz are polycrystalline, feldspar (anorthite) occurs as fine-grained euhedral to subhedral crystals scattered in the matrix, calcite occurs as very fine-grained (micrite), iron oxides and opaque minerals occur as very fine to medium-grained, gypsum occurs as fibrous aggregates to needle-like crystals, and some irregular pore spaces and fine channels are detectedBack to article page