Mercury content and petrographic composition in Pennsylvanian coal beds of Indiana, USA Maria Mastalerz a, ⁎ , Agnieszka Drobniak a , Gabriel Filippelli b a Indiana Geological Survey, Indiana University, 611 North Walnut Grove, Bloomington, IN 47405, USA b Department of Geology, Indiana University Purdue University, Indianapolis, IN 46202, USA Received 1 December 2004; received in revised form 24 October 2005; accepted 24 October 2005 Available online 23 February 2006 Abstract A suite of high volatile bituminous coals of Pennsylvanian age from Indiana has been studied for their mercury (Hg) concentration and relationship between mercury content and maceral and lithotype composition. The coals ranged in Hg content from 0.02 in the Danville Coal Member to 0.31ppm in the Upper Block Coal Member. Our study indicates that relationships between petrographic composition of coal and mercury content are site specific. This lack of a consistent relationship is explained by the fact that most Hg occurs in pyrite and not in the organic matter itself. Comparison of Hg content in durain/vitrain pairs shows that durain has more frequently a higher Hg content than vitrain, but the difference in frequency is inconsequential and shows no consistent pattern for a single coal bed or a single location. We suggest that increased concentration of Hg in vitrain is related to the presence of epigenetic pyrite in cleats. © 2006 Elsevier B.V. All rights reserved. Keywords: Mercury; Coal; Lithotypes; Macerals; Illinois basin 1. Introduction There is much evidence that mercury in coal is associated dominantly with sulfides. The association of Hg with pyrite, especially late-stage (epigenetic) pyrite, has been widely demonstrated for many coals world- wide (Finkelman, 1981; Swaine, 1990; Goodarzi and Swaine, 1993; Finkelman, 1994; Goodarzi, 2002). More recently, Kolker et al. (2002) demonstrated this association for numerous U.S. coals. In addition, a recent study of the coals from the Black Warrior Basin in Alabama document that high Hg is associated domi- nantly with late-stage pyrite that occurs as overgrowth and in veins (Diehl et al., 2004). Significantly less Hg seems to be associated with other geochemical entities such as silicates, carbonates, or organic fractions. In our recent study of Indiana coals (Pennsylvanian) we also suggested that Hg was associated, to a large extent, with mineral matter, and in particular with pyrite (Mastalerz and Drobniak, 2005). The association with pyrite was especially distinct in coals that had high amounts of pyritic sulfur, for example, the Springfield Coal Member and the Hymera Coal Member. In Indiana coals that have low pyritic sulfur contents, however, Hg associations with pyrite are less distinct. In the low-sulfur Danville Coal Member, Hg has no relationship to pyritic sulfur or to total sulfur and a slight negative correlation to ash yield (Mastalerz and International Journal of Coal Geology 68 (2006) 2 – 13 www.elsevier.com/locate/ijcoalgeo ⁎ Corresponding author. Tel.: +1 812 855 9416. E-mail address: mmastale@indiana.edu (M. Mastalerz). 0166-5162/$ - see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.coal.2005.10.002