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Fig. 9 | Heritage Science

Fig. 9

From: Geoenvironmental investigation of Sahure’s pyramid, Abusir archeological site, Giza, Egypt

Fig. 9

a 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 detected

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