Bethlehem Steel 2: Jack Crelling, Bethlehem Steel Homer Labs, and effects on my own research direction and insight

In my previous post on Bethlehem Steel, I mentioned that I had worked for and taken Coal Petrology courses at Southern Illinois University from a professor who had worked in Bethlehem Steel research labs. That was Dr. John C. Crelling, who recently died at the too-young age of 77. Jack was not just a teacher to me, but a family friend.

Jack Crelling, after getting his PhD at Penn State and service in the Army during Vietnam (of which he was very proud), worked at the Homer Research Laboratory of Bethlehem Steel on South Mountain in Bethlehem, Pennsylvania, ~ 1 ½ miles up from the blast furnaces. He was Geologist-in-Charge of the Coal Petrography Laboratory, Coal and Coke Section, from 1972-1977. From 1978-2006, Jack taught at Southern Illinois University (SIU), Carbondale, IL, continuing his research after retirement as Research Faculty. A summary of his expansive and innovative research interests are at https://geology.siu.edu/faculty-staff/research-faculty/crelling.php https://geology.siu.edu/faculty-staff/research-faculty/crelling.php ; his curriculum vitae with extensive publication list and professional society awards can be found at https://geology.siu.edu/_common/documents/faculty-cv/crelling-cv.pdf ; and a memorial is in the December 2018 issue of the newsletter of The Society for Organic Petrology (https://www.tsop.org/newsletters/35_4.pdf , page 9).

I worked for Jack in his SIU Coal Characterization Lab starting in December 1982, a few months after my arrival in Carbondale as a faculty wife. My initial job was programming, in BASIC, the code for collecting spectral epifluorescence data from liptinite macerals under a microscope through an analog-digital converter. The computer was a state-of-the-art Apple II, and I had 512K of space for the program!! Eventually over the next 2 ½ years, I also did petrographic work, learning first macerals and point-counting through Jack’s Coal Petrology courses, and then vitrinite reflectance directly in the lab.

When I arrived at SIU, I had just completed a Master’s in Geology at Dartmouth College, New Hampshire, USA (birthplace of BASIC), doing a mapping thesis in nearby sillimanite-grade thrice-deformed granite-intruded Silurian-Devonian rocks that were mostly turbiditic flysch of the Early Devonian Acadian orogeny. I enjoy putting together a regional story of deposition, deformation and temperature history. However, the trajectory of my career interest changed after taking Jack’s coal classes and working in his lab, focusing no longer on thermal evolution of high-grade metamorphic rocks, but instead on “metamorphism” or diagenesis of sedimentary and very-low-grade metamorphic rocks.

Below are three significant contributions Jack had on either the direction of my research interests or petrologic knowledge. The latter derived from Jack’s Bethlehem Steel experience: 

1) Change in research interest: Besides being useful for my new job in his lab, I took Jack’s Coal Petrology (microscopic study of coal) course, spring semester 1983, because this was an earth science topic not available at my previous educational institutions and would fill a gap in my geologic knowledge. We used Stach’s Textbook of Coal Petrology (3^rd edition) which covered origin of coal and macerals, changes in coal rank with burial and temperature (peat to lignite to bituminous to anthracite), coal utilization, and applications of the microscopic study of coal. Towards the end of the course, Jack displayed a chart (Figure 1) that showed the relationship of coal rank to various chemical and physical parameters and, importantly, to the zones of oil and gas generation. I remember the words that popped into my head, “So that’s how it works!” That chart, somehow more than anything discussed in my earlier petroleum geology course, graduate clay mineralogy course, or graduate metamorphic petrology class, tied together for me what is going on, invisible to the naked eye, during diagenesis in sedimentary rocks, particularly the windows of oil and gas generation, in relation to coal ranks, and vitrinite reflectance. That the chart indicates the eventual graphitization of anthracite, the realms of sedimentary and metamorphic rocks became transitional, no longer compartmentalized, as many of us unconsciously make them. I decided then to focus my interest in “metamorphism” and thermal history on the diagenetic to very-low-grade-metamorphic temperature range where the coal-petrographic maturation technique, vitrinite reflectance, would be applicable.

 

FIGURE 1: The probable figure from Stach’s Textbook of Coal Petrology Jack Crelling showed in his Coal Petrology course that changed the trajectory of my research career.

 2) Pseudovitrinite and awareness of oxidation and variable preservation of vitrinite: The macerals within the vitrinite maceral group represent various degrees of chemical and physical change during burial, not including pre-depositional combustion, of woody plant material. Telinite is identified clearly by preservation of woody cellular structure; it is the maceral used in vitrinite reflectance measurement. In collotelinite, texture is more homogeneous with cell walls possibly only barely visible. The loss of cell structure in collotelinite and collodetrinite (gelified vitrinite detritus in which other particles like spores, charcoal can be embedded) indicate an increased physical breakdown of woody material during early stages after deposition (peatification) and then subsequent early coalification. In addition to these vitrinite group macerals, there are unofficial maceral designations for woody material subjected to more oxidizing (less reducing) conditions which may also preserve wood cellular structure and, additionally, increase reflectance. A higher-reflecting telinite with distinctive slits was identified by Benedict and others (1968*) of Bethlehem Steel and called “pseudovitrinite” (Figure 2). In the coking process, it acts as a semi-inert, not totally softening and going through the liquid-crystal mesophase that vitrinite does. Benedict and colleagues found the amount of pseudovitrinite in a coal affected various performance characteristics both in the coke ovens and of the resulting coke in the blast furnace.

           Due his Bethlehem Steel background, pseudovitrinite was a maceral we counted during in Jack’s courses* and during coal characterization in the lab (Figure 3). The intellectual seed planted by working with “pseudovitrinite” was that there are pre-to syn-depositional oxidative processes that can affect the reflectance of vitrinite. These processes may be autochthonous, occurring in the coal swamp if mires dry out and are not continuously buried in a wet reducing environment, or allochthonous during punctuated transport of trees and dead wood downstream before deposition in fluvial, lacustrine or marine sediments. Kaegi (1985*) used the term “oxyvitrinite” to refer to higher-reflecting non-slitted vitrinite. However, more than a few geologists assume that any higher-reflectance vitrinite must have been eroded from an older exhumed rock, calling that population “recycled vitrinite”. I have only rarely identified vitrinite or coaly particles (twice?) that definitely had been previously buried. To assume all higher-reflectance vitrinite is eroded coaly material with a previous maturation history ignores the taphonomy of organic matter and oxidizing processes either in swamps or water-born transport. (Certainly, any vitrinite found in marine rocks had to travel from land to get there!)

FIGURE 2: Pseudovitrinite showing remnant woody plant structure and the trademark slits that differentiate pseudovitrinite from telinite. From Crelling’s Petrographic Atlas of Coals and Carbons.

FIGURE 3: Standard maceral point count sheet from Jack’s lab, this one used in an Advanced Coal Petrology Coal-of-the-Week assignment, 1983. Note the pseudovitrinite among white-light maceral categories.

3) Coke petrology- applications to and understanding of fly ash petrology: Although introduced in undergraduate Coal Petrology class, Jack’s Advanced Coal Petrology class included a larger focus on the petrography of industrial coke, definitely a consequence of his Bethlehem Steel experience, although his Master’s research at Penn State was on natural cokes near igneous intrusions. One might wonder, why should I care about coke petrography if I am never going to work for a steel company? This knowledge, I have found, can be a valuable tool in the study of fly ash, a component in modern sediments deposited since 1800. Counting volume of fly ash particles in Central Park (NYC) sediments, I made notes on the “coke” texture of particles in order to identify rank range of contributing coals (currently collecting vitrinite reflectance data on the samples to compare that with the broader rank categories from coke-texture). I find familiarization with coke petrography and the physical processes of carbonization and combustion that produce structures in coke and fly ash particulates invaluable for understanding what one is seeing microscopically. In the last few years, the International Committee on Coal and Organic Petrology (ICCP), the international organization responsible for standardizing coal and organic petrology nomenclature and petrographic accreditation, has been working on a petrographic fly ash classification scheme *. Ideally, the classification should be able to be used by petrographers based solely on particle morphological and textural characteristics, but to apply classification categories like “fused” and “unfused” successfully, when one is not familiar with physical and chemical changes during combustion, is challenging.  (Fused carbons are primarily bituminous coal vitrinites that have softened and lost any gases producing new mosaic or ribbony textures in a solid carbon char before final combustion consumption; unfused carbons are inert macerals, anthracites, rogue unburnt vitrinite.) Not all coal and organic petrographers get coke or combustion education as part of their coursework or training, but due to Jack’s steel industry employment, I luckily received more thorough instruction than many! Photomicrographs here are from Crelling’s Petrographic Atlas of Coals and Carbons on the Southern Illinois University, Dept. of Geology, website, a useful reference tool Jack created.

FIGURE 4: Combustion char with mosaic texture. From Crelling’s Petrographic Atlas of Coals and Carbons.

FIGURE 5: Metallurgic coke from high volatile bituminous coal showing mosaic texture. From Crelling’s Petrographic Atlas of Coals and Carbons.

  

 *Benedict, L.G., R.R. Thompson, J.J. Shigo III and R.P. Aikman, 1968, Pseudovitrinite in Appalachian coking coals: Fuel, v. 47, p. 125-143.

Crelling, J.C., 1986, The occurrence and properties of pseudovitrinite (abs): Abstracts and Program, The Society for Organic Petrology (TSOP), 3^rd annual meeting, Calgary, p. 28-29. http://archives.datapages.com/data/tsop/TSOPv3_1986/crelling.htm (page 28 only; accessed February 2019)

Kaegi, D.D., 1985, On the identification and origin of pseudovitrinite: International Journal of Coal Geology, v. 4, p. 309-319.

Suárez-Ruiz, I., Valentim, B., Borrego, A.G., Bouzinos, A., Flores, D., Kalaitzidis, S., Malinconico, M. L., Marques, M., Misz-Kennan, M., Predeanu, G., Montes J.R., Rodrigues, S., Siavalas, G., Wagner, N., 2017, Development of a petrographic classification of fly-ash components from coal combustion and co-combustion. (An ICCP Classification System, Fly-Ash Working Group–Commission III): International Journal of Coal Geology, v. 183, p. 188-203. doi.org/10.1016/j.coal.2017.06.004