Laboratory
SCIENTIFIC CAPABILITIES AND APPLICATIONS
The Organic Petrology Laboratory at the U.S. Geological Survey in Reston, Virginia, exists to produce quantitative analytical data on the organic composition and thermal maturity of coal and petroleum source rocks. This is accomplished through the petrographic examination of samples with incident light microscopes, using tungsten halogen and xenon gas discharge light sources. Organic composition of samples is determined via a point-counting examination with a mechanical stage. Thermal maturation analysis is conducted by measuring sample reflectance with a photometer and peak detection software. Textural and compositional analysis of dispersed organic material in rock samples also is accomplished through transmitted light investigations. Petrographic analyses are conducted by or under the supervision of petrographers with official accreditation from the International Committee for Coal and Organic Petrology (links to accreditation certificates).
Information about the organic composition and the thermal maturity of coal and petroleum source rocks can be used in a variety of applications. Maturation studies include coal rank and hydrocarbon source rock maturity assessments, which are applied in the exploration for and evaluation of energy resources. Knowledge of the organic composition of coals can be applied to predict the quality of coal resources, to improve mining strategies, and to predict coal behavior during carbonization or combustion processes. Information about the types of organic material present in petroleum source rocks is used to determine their oil- versus gas-prone hydrocarbon potential and to assess paleoenvironmental conditions of deposition.
FACILITIES
Facilities at the Organic Petrology Laboratory include a sample preparation laboratory equipped with sample dividers, sieves, a Buehler Simplimet 3000 automatic mounting press, and a Buehler Ecomet 4 variable speed grinder-polisher. The sample preparation laboratory also contains a fume hood for preparation of larger sample blocks via epoxy resin mounts.
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| Buehler Simplimet 3000 automatic mounting press for sample preparation via heat-setting transoptic powder. |
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Buehler Ecomet 4 variable speed grinder-polisher for preparation of polished sample briquettes. |
The microscope laboratory is equipped with an incident light Leitz Orthoplan microscope with photometer and peak detector for reflectance analysis, a Leica DMRX with mechanical stage and tungsten halogen and xenon gas discharge light sources for incident light compositional analysis, and a Leitz Orthoplan for examination of rock thin sections in transmitted polarized light.
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| Leitz Orthoplan incident light microscope with photometer and peak detection equipment for thermal maturation analysis. |
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Leica DMRX incident light microscope with mechanical stage and Swift F automated point counter for analysis of organic composition of coal and rock samples. |
The Organic Petrology Laboratory also contains a Leica M420 binocular microscope for macroscopic examination of sample mounts or larger sample blocks. A Leica DFC 480 digital camera can be mounted to each microscope for image capture. Image analysis is conducted using ImagePro Plus software routines.
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| Leitz Orthoplan transmitted light microscope with Swift F automated point counter for textural and compositional analysis of rock samples in thin section. A Leica DFC 480 digital camera is mounted on the microscope tube for image capture. |
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Leica M430 binocular microscope. |
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U.S. Department of the Interior |
U.S. Geological Survey
