## 4 Results
### Petrography
#### 4.1.2 Western Gahirat Marble  
Mineralologically, the western part of Gahirat Marble is mainly composed of calcite (92-98%) with minor amounts of quartz (0.5-1.5%), dolomite (0.5-2%), ore minerals (1-3%), muscovite (0.5-1.5%), chlorite (0.5-1%), and phlogopite (up to 0.5%) (Figure 4, Table 1).  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**Sample** & **Calcite** & **Dolomite** & **Quartz** & **Muscovite** & **Philogopite** & **Chlorite** & **Biotite** & **Gamet** & **Opaque** \\ \hline GMGL1 & 94 & 0.5 & 0.5 & 1 & - & - & 1 & 1 & 2 \\ GMKB1 & 96 & - & - & 1 & - & 0.5 & 1 & 1 & 0.5 \\ GMK1 & 95 & 1 & - & 0.5 & - & - & 0.5 & 0.5 & 2.5 \\ GMB1 & 96 & - & - & 1.5 & - & 0.5 & 0.5 & - & 3 \\ GMGT1 & 95.5 & & 0.5 & 0.5 & - & 0.5 & 0.5 & 1 & 1.5 \\ GMC1 & 97 & - & 0.5 & 1 & 0.5 & - & - & - & 1 \\ GMG1 & 98 & 0.5 & - & 0.5 & - & - & - & - & 1 \\ GMCG1 & 92 & 1.5 & 1.5 & 0.5 & 0.5 & 1 & - & - & 3 \\ GMG21 & 98 & - & - & - & 0.5 & 0.5 & & & 1 \\ GMG22 & 97 & 0.5 & 0.5 & - & - & - & & 2 \\ GMD1 & 93 & 2 & 1.5 & 0.5 & - & 1 & & 2 \\ GMA1 & 96 & 1 & 1.5 & 0.5 & - & - & & 1 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Modal mineralogy (Vol. %) of Gahirat Marble.  
Figure 3: Photomicrograph of Gahirat Marble: (**a**) large crystals of calcite (cal) having very few micro fracture GMGL1, (**b**) calcite grains showing twin lamellae having homoplastic texture with few traces of ore mineral GMKB1, (**c**) shows both visible and invisible twin lamellae grains of calcite in GMK1, (**d**) shows large interlocking crystals of calcite with biotite mica with significantly less fracture grain GMB1, (**e**) the muscovite grains showing alignment in two direction twin lamellae GMA2 showing minor fractures in calcite crystal, (**f**) showing garnet grains between the calcite GMGT1.  
The calcite crystals revealing the homoblastic texture of calcite grains exhibit twin lamellae having a straight boundary shape developed in GMA1 due to the mechanical deformation that occurred during regional metamorphism (Figure 4f). This lamellae structure does not affect the strength of the marble because the grains of calcite are mostly sutured and interlocked with curved boundaries (Figure 4b). In sample GMD2, the boundaries of calcite grains were mostly sutured and rarely curled (Figure 4b,c). The shape of the calcite crystal boundaries reflects the type of metamorphic events that occurred during the marble formation. Straight boundaries are typically the result of a long metamorphic time (Figure 4a,d), whereas sutured boundaries in strongly interlocked crystals are the result of unstable conditions reached after relatively short metamorphic events (Figure 4c). On the other hand, more or less curved crystal margins are associated with intermediate metamorphic conditions. The medium-grained calcite is surrounded by fine-grained minerals such as dolomite, ore minerals, and mica (Figure 4c,e). The minor dolomite crystals grew on the calcite crystals at a fine-grained level. The maximum grain size of the calcite or dolomite individuals is also an important diagnostic parameter strictly related to the degree of metamorphism, i.e., to the maximum temperature reached by a marble formation during its evolution [46]. The presence of muscovite, chlorite, and phlogopite suggests that the Gahirat Marble was subjected to greenschist metamorphism.