X-ray diffraction analysis (XRD)

This is a qualitative and semi-quantitative method used for analysis of crystalline matter, and is essential for determination of the mineralogical composition of fine-grained sediments like shale.

Equipment: A modified Philips PW1710 diffractometer with spinner automatic sample changer.

Left: Rock fragments are ground to powder. Right: X-ray diffractogram of fine fraction of shale in dry state and after treatment with ethylene glycol.

Scanning electron microscopy (SEM)

The SEM is mainly used for examination and visualization of the distribution of minerals occurring in rocks, and for visualization of experimental results. Element distribution provided by energy dispersive X-ray analysis helps to identify the minerals present.

Equipment: JEOL 733 superprobe with SEI, BSE, X-ray and cathodoluminescence detectors and cryogenic unit.

Left: Secondary electron image showing portlandite Ca(OH)2 precipitated on a concrete surface during storage in water. Right: Secondary electron image illustrating the occurrence of grain-coating smectite in Red Wildmoor sandstone.

Transmitted light microscopy

Examination of thin sections by traditional petrographic microscope provides textural parameters like grain size, sorting and lamination in sandstone, reveals the occurrence and distribution of cement in pores, and visualizes the results from rock mechanical tests on rock samples. Both overview and detailed images are provided. Mineralogical composition is obtained by modal analysis (point counting).

Equipment: Leitz Laborlux 11 polarization microscope, Leica M420 photomacroscope, Leica DFC420 digital camera.

Left: Quartz cement precipitated inside pore lined by chlorite. Right: Visualization of extensive grain crushing in sandstone submitted to a rock mechanical test.

Additional services

• Cation exchange capacity (CEC) measurements by using spectrophotometer (cobalt hexamine method).
• Density and water content determination by buoyancy and devapourization method (used for shale and tight rocks).