Phase identification and Rietveld refinement of Connemara (Irish) Marble

Connemara Marble is unique in the sense that it is only found in one place on earth - in Galway County on the scenic west coast of Ireland. Inland from this coastal region is a series of 12 mountains known as the 12 Bens. This is where the unique marble is quarried. A combination of different types of minerals is what makes this beautiful green marble so unique.

Normally, marble is composed of a limestone (CaCO₃) mineral exposed to high temperatures and pressure causing a metamorphic change in the overall texture and appearance of the rock.

However, in addition to containing a limestone mineral (calcite), there are 3 other phases belonging to the serpentine mineral family found in Connemara Marble. The main polymorphic forms are chrysotile, antigorite, and lizardite. X-ray diffraction is a viable technique to identify and pinpoint the exact phase of the serpentine family.

Figures 2 shows the specimens of Connemara marble that were pulverized and analyzed with the Rigaku's MiniFlex benchtop diffractometer.

Figure 2

The obtained diffraction pattern and the results of phase identification are shown in Figure 3 and Table 1. 

Figure 3

A Rietveld analysis was performed using the model obtained from these phases and quantitative results are shown in Table 1 and Fig 4 in the form of a pie chart.

Figure 4