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Coal & coke petrography

Coal petrography is performed to characterize coals, particularly the organic portion coals. This test-work may be required for initial characterization of exploration samples, for determination of the utilization potential of a coal, for certification of shipment quality or for other technical applications. A similar analysis can be performed on coke samples where coke microtexture analysis provides an indication of the proportion of fusible and infusible components in the coke.

Coal Reflected Light Microscopy

Process overview

Coal petrography is performed on a coal sample with a 1mm particle top-size that has been crushed in a particular way to produce a minimum of fines. This coal sample is mixed with a binder, such as acrylic resin, and the mixture is placed into a mold and allowed to set. Once the petrographic block is solid, it is removed from the mold and subsequently cut and polished to produce a surface that is free of scratches and relief. This is placed under a reflected light optical microscope to perform the analyses.


There are two standard coal petrographic analyses:

ALS also perform non-standard petrographic analyses:

Control systems

To ensure ALS delivers reliable results, ALS' petrographers are evaluated and certificated by the International Committee for Coal and Organic Petrology (ICCP). The petrography unit is also accredited to ISO 17025 for maceral analysis according to AS 2856.2 and ISO 7404.3 and to vitrinite reflectance according to AS 2856.3 and ISO7404.5.

Laboratory support

Coal petrography is not usually performed as a standalone test but rather as a component in a comprehensive testing program including pilot-scale coal carbonization tests. ALS has well-equipped laboratories capable of performing a broad range of coal analysis through an extensive coal laboratory network.

Related topics

Discharging Coke from Oven

Pilot-scale Carbonization

Coal petrography is often conducted in conjunction with carbonization testing. For further information on ALS’ pilot-scale coke oven refer to