ASTM D2798-11

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Designation:D2798–09a Designation: D2798 – 11
Standard Test Method for
Microscopical Determination of the Vitrinite Reflectance of
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Coal
This standard is issued under the fixed designation D2798; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This test method covers the microscopical determination of both the mean maximum and mean random reflectances
measured in oil of polished surfaces of vitrinite and other macerals present in coals ranging in rank from lignite to anthracite. This
test method can be used to determine the reflectance of other macerals.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory
limitations prior to use.
2. Referenced Documents
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2.1 ASTM Standards:
D121 Terminology of Coal and Coke
D388 Classification of Coals by Rank
D2797 Practice for Preparing Coal Samples for Microscopical Analysis by Reflected Light
3. Terminology
3.1 Definitions—For definitions of terms, refer to Terminology D121.
3.2 Abbreviations:
3.2.1 R R max—mean maximum reflectance measured in oil.
max o
3.2.2 R R ran—mean random reflectance measured in oil.
m o
3.2.2.1 Discussion—Other organizations may use other abbreviations for mean maximum and mean random reflectance.
4. Summary of Test Method
4.1 Thereflectanceofthemaceralvitriniteorothermaceralsisdeterminedinthistestmethodbyilluminatingapolishedsurface
of a section of coal in immersion oil using a microscopic system that photometrically measures the amount of light reflected from
the surface. The reflected light is recorded in percent reflectance after calibration of photometric equipment by measuring the
reflected light from standards of reflectance as calculated from their refractive indices.
5. Significance and Use
5.1 The mean maximum reflectance of the vitrinite component in coal as determined by this test method is often used as an
indicator of rank as presented in Classification D388, independent of petrographic composition, and in the characterization of coal
as feedstock for carbonization, gasification, liquefaction, and combustion processes.
5.2 This test method is for use in scientific and industrial research.
6. Apparatus
6.1 Microscope—Any microscope equipped for reflected light microscopy (such as a metallurgical or opaque-ore microscope)
can be used, provided the lens combination of objective and eyepieces permits examination of the specimen at a magnification
between 400 and 3 750, such that particles of 1 µm can be resolved. The objectives shall be constructed so that samples can be
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This test method is under the jurisdiction ofASTM Committee D05 on Coal and Coke and is the direct responsibility of Subcommittee D05.28 on PetrographicAnalysis
of Coal and Coke.
Current edition approved Sept. 1, 2009.April 15, 2011. Published September 2009.June 2011. Originally approved in 1969. Last previous edition approved in 2009 as
D2798 – 09a. DOI: 10.1520/D2798-09A.10.1520/D2798-11.
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volume information, refer to the standard’s Document Summary page on the ASTM website.
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D2798 – 11
examined in oil with plane-polarized light and have the highest quality of antireflection coatings. The microscope shall be able to
project an image at similar magnification to a photomultiplier tube and to support the photomultiplier tube housing. Means shall
be provided to position the tube housing laterally to obtain maximum response. The microscope shall have a circular stage that
is capable of rotating a specimen through 360°. The mechanical stage attached to the microscope stage shall enable the analyst to
move the specimen accurately (within 0.1 mm) to a given field location.Acombination of objective and circular stage shall permit
centering. The vie
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