Coal Macerals Scroll | Petrographic Atlas | SIU

Description:The uniform gray material is vitrinite showing remnant plant cell structure that has survived the coalification process. In the ICCP classification this material is– telovitrinite but also called pseudovitrinite. The slit structures, in this case parallel to the direction of the cell structure, are common in this maceral.

Description: A drawing of fossil tree bark from a Lepidodendron tree of Carboniferous age from the Caseyville Formation, Union Count, IL.This drawing is based on the work of Jennings (1990).

Description: The uniform gray material is vitrinite showing remnant plant cell structure that has survived the coalification process. In the ICCP classification this material is  telovitrinite but also called pseudovitrinite. The slit structures, in this case perpendicular to the long axis of the cell structure, are common in this maceral.

Description: Telovitrinite (pseudovitrinite) on the right and detrovitrinite on the left of frame. Note the remnant cell structure and the serrated edges along the fracture in the telovitrinite. The lower reflectance and the included macerals of liptinite (dark) and inertinite (bright) in the detrovitrinite are characteristic of this maceral. 

Description: Vitrinite macerals:  Large particle of telovitrinite showing remnant plant cell structure (upper right) with adjacent particles of detrovitrinite. The detrovitrinite shows no cell structure and acts as a matrix for dark particles of liptinite and bright particles of inertinite macerals.

Description: A large particle of detrovitrinite at left, note the other liptinite macerals (dark) and inertinite macerals (light) included. The particle on right with no inclusions and higher reflectance is telovitrinite.

Description: A particle of detrovitrinite with inclusions of megaspores and microspores (dark) and semifusinite and fusinite (bright).  The detrovitrinite acting as a matrix for other macerals is characteristic.

Description: The rounded medium gray particles are vitrodetrinite in a matrix that is mostly mineral matter.The detrovitrinite is vitrinite dispersed in a sedimentary rock.

Description: The uniform light gray material is vitrinite showing a well-developed remnant cell structure. The cells here are filled with much darker resinite. Compare the cell fillings here with the cell fillings in frames MA1 and MA3. The darker tone here indicates resinite. This is confirmed in frame MA 10 which is the same field in blue-light illumination.

Description: Same field of view as MA09 but in blue-light illumination. Note the yellow fluorescence of the resinite and the apparent lack of fluorescence of the vitrinite. Differences in fluorescence properties are commonly used to distinguish macerals from each other.

Description: The large low reflectance structureless ovoid of resinite is a typical occurrence of this maceral. The dark brown color is commonbut the color can range from black to light gray in reflected white light.

Description: Same field of view of view as MA11 but under blue-light illumination. The yellow fluorescence of the resinite is light excited from the resinite. The presence of a dark rim around the outer surface of the maceral is a common feature and usually interpreted as a reaction rim caused by weathering.

Description: The large ovoid of resinite is darker than normal for a resinite maceral.Note how the other macerals adjacent to the resinite are compressed around it. This feature is usually interpreted to indicate that the resinite was solidified before it was incorporated into the peat.

Description: Same field of view as MA13 under blue-light illumination showing a resinite ovoid fluorescing a bright yellow. The presence of a dark rim around on the outer surface of the maceral is a common feature and usually interpreted as a reaction rim caused by weathering. 

Description: Angular particles of concentrated resinite fluorescing different colors under blue-light illumination. Green, yellow, and orange are the most common fluorescent colors. This field shows a number of crushed resinite particles that have been excited wih ultra-violet light which causes the resinite to ...read full profile >>

Description: Under blue-light illumination,an occurrence of cleat-filling resinite on the right and the host coal on the left. Note the swirling flow structure of fine coal particles flowing from the host coal into the vein filling. This structure indicates that the cleat-filling resinite was fluid at the time the fine particles were incorporated.

Description: Under blue-light illumination the cleat-filling resinite fluoresces a bright greenish-yellow. Note the non-fluorescing particles included in the cleat. These are coal xenoliths swept into the cleat when the mobile resinite was injected into the cleat.

Description: Under blue-light illumination, an ovoid of resinite fluoresces bright yellow with a darker center. This is a zoning texture possibly caused by phase separation or by multiple periods of resinite intrusion.

Description: Under blue-light illumination,two intersecting resinite veins. The vertical vein fluoresces bright yellow while the horizontal vein fluoresces a much darker yellow. Because the vertical vein is cut by a perpendicular vein, the vertical vein must have been emplaced first. These cross-cutting vein indicate two different periods of resinite injection.

Description: The dark folded structure in the center of the field is a typical megaspore. It shows the characteristic flattened-sphere structure resulting in a bilateral symmetry around a central fissure. The much smaller dark bodies are microspores with less developed symmetry.

Description: Same field of view as MA20 under blue-light illumination. The megaspore fluoresces with a dull yellow color and the grainy texture is enhanced.

Description: The dark feature in the center of the frame is sporinite. It is characterized by its low reflectance and bilateral symmetry.  The orange spot is due to internal reflections and is a common feature in megasporinite. A smaller sporinite maceral is also seen in the lower right.

Description: Same field of view as MA22 under blue-light illumination. The sporinite macerals in this frame fluoresce a bright yellow. Note how the fluorescence reveals more details of the surface structure and the presence of microsporinite within the vitrinite matrix.

Description: Sporinite is present as small dark features in this typical occurrence with higher-reflecting inertinite macerals.

Description: Same field of view as MA24 under blue-light illumination. Note how the yellow fluorescing sporinite stands out. Thus, when petrographic analysis is done in blue light, the liptinite counts are always higher than in normal white-light analysis.

Description: The large dark feature is crassicutinite, a maceral derived from thick-walled. Note that one side is flat while the other side is crenulated. Although the nature of the crenulations varies, the difference in the two surfaces is typical.

Description: Same field as MA26 under blue-light illumination. Note the yellow fluorescence and the enhanced texture.

Description: The dark stringers running across the field are tenuicutinite (thin-walled cutinite). 

Description: Same field of view as MA28 under blue-light illumination. Note the yellow fluorescence and the crenulation on some of the surfaces. Also note how these features are easier to distinguish when the maceral observed under fluorescent light.

Description: The large dark linear feature is cutinite.  Note the internal reflections and the lack of observable detail.

Description: Same frame as MA30 under blue-light illumination. Note the crenulations and the enhanced detail observable under fluorescent light. 

Description: The open cell-wall structure with a very high reflectance is characteristic of fusinite. The cell-wall structure is believed to be charred and coalified remnant plant cell-wall structure.Charred wood (charcoal) has a similar appearance.

Description: This particle of fusinite shows the high reflectance and open cell structure typical of fusinite. Note also the preservation of the delicate structures of the parent plant.

Description: The brightest material in this frame is fusinite and the lower reflectance material is semifusinite. Note that both macerals have the characteristic open cell texture. 

Description: The three kinds of material in the upper three-fourths of this frame are semifusinite. All three have open-cell structure and reflectances between that of vitrinite and fusinite, as is characteristic of these macerals. The darker layer at the bottom of the frame is vitrinite and the very bright particle ...read full profile >>

Description: The two bright particles of secretinite (previously called resino-sclerotinite) show the high reflectance and lack of cell structure typical of these macerals. Similar macerals with a reflectance in the semifusinite range are called semi-macrinite.

Description: The donut shaped feature in the center of the field is funginite and is believed to be derived from fungal material. The uniform gray material is vitrinite and the very bright stringer is fusinite.

Description: The multi-celled bodies in this frame are funginite and are believed to be derived from fungal material. These features are not seen in coals of Carboniferous age.

Description: The fine grained material is micrinite. It is characterized by its high reflectance and very fine size. In this example, the form outlined by the fine particles is similar to cutinite and the micrinite may be derived from it.

Description: The fine grained material is micrinite. It is characterized by its high reflectance and very fine size. In this example, the forms outlined by the fine particles are similar to sporinite and the micrinite may be derived from altered sporinite.