| Construction material | Limestone | Granite |
| Rock name | Fossiliferous limestone (Biomicrite) | Altered perthitic granite |
| Rock type | Organic, sedimentary rock | plutonic, felsic igneous rock |
| Texture | The rock is very fine to fine-grained. Microfossils are scattered in very fine-grained of calcite (micrite matrix) and filled by recrystallized carbonate (sparitic calcite) and some microfossils filled by micritic calcite | The rock is medium to coarse-grained showing granular, hypidiomorphic, perthitic and piokilitic textures. |
| Mineral composition | The rock is very fine to fine-grained and composed mainly of carbonates (mainly calcite) as the essential component associated with minor amounts of iron oxides and opaques and rare amounts of phosphate minerals, microcrystalline quartz and clay minerals. Carbonates (mainly calcite) represent the matrix of the rock and occur as very fine-grained, anhedral crystals interlocking to each other. Significant number of microfossils and shell fragments in different shapes and sizes are observed scattered in the matrix of the rock and filled by recrystallized carbonates (sparite) and some microfossils filled by micrite. Opaque minerals occur as very fine to fine-grained aggregates and scattered commonly at the boundaries of the microfossils. Phosphate minerals (collophane) occur in rare amount and scattered in carbonate matrix. Microcrystalline quartz occurs in rare amount and observed distributed in the rock. Few irregular pores are observed in the rock as shown in Figure 10 the samples investigated under polarizing microscope Crossed Nicole and the samples investigated under polarizing microscope (PLM) | The rock is composed mainly of alkali feldspar (microcline & orthoclase perthite), quartz, plagioclase, biotite and hornblende together with accessory of titanite, zircon, apatite and opaque minerals as shown in Figure 12. Secondary minerals are represented by sericite, carbonates, clay minerals, chlorite and iron oxides. Alkali feldspar (microcline & orthoclase perthite) is the most abundant constituent of the whole rock. It is coarse-grained, generally anhedral crystals and slightly altered and turbid with clay minerals. Some crystals of feldspars are deformed and corroded due to mild deformation effect. Quartz is essential mineral constituent occurs as fine to coarse-grained, anhedral crystals and filling the interstitial spaces between feldspar crystals. It shows stretched crystals, corroded, granulated, curved boundaries and deformed due to deformation effect. Plagioclase is medium to coarse-grained, subhedral platy in form and shows distinct lamellar twinning and partially altered to sericite and carbonate minerals. It presents also as irregular lamellae, thin films and fine inclusions intergrowths in microcline & orthoclase perthite showing perthitic texture. It is also somewhat deformed and shows curved lamella. Biotite occurs as fine to medium-grained tabular, flaky crystals at the interstices of feldspars and quartz. It is strongly pleochroic; and partially to highly altered to chlorite with liberation of iron oxides at its cleavage planes and borders. Locally radioactive halos are noticed within biotite crystals (probably due to the presence of radioactive zircon). Hornblende occurs as fine to medium-grained tabular, prismatic crystals at the interstices of feldspars and quartz. It is commonly associated with biotite; and partially to highly altered to chlorite with liberation of iron oxides at its cleavage planes and borders. Titanite is very fine to fine-grained; subhedral to euhedral rhombic and/or acute crystals, mainly associated with altered biotite and hornblende (most probably as alteration product). Zircon is very rare, extremely fine-grained, euhedral in form and generally noticed in association with biotite and hornblende. |
| Images | Figure 10 | Figure 12 |
| Alteration | Recrystallization of primary carbonate (calcite) detected in the microfossils and shell fragments to form a coarser grained calcite. Some pore spaces are detected in the sample due to dissolution of the original constituents such as fossils shell as shown in Figure 11. | The rock is affected by alteration and deformation over original constituents. Alkali and plagioclase feldspars are partially altered to sericite, carbonates and clay minerals. Mafic minerals (biotite and hornblende) are partially to highly altered to chlorite with liberation of iron oxides at its cleavage planes and borders. The rock affected by deformation and granulation over essential constituents especially in quartz and mafic minerals as shown in Figure 13. |