Mineral Barnetta Marcellusa Mancosb Eagle Fordc (wt%) (wt%) (wt%) (wt%) Quartz  35-50 10-60 36-43.4 9 Clays, primarily illite 10-50  10-35 30.2-42.4 26 Calcite, dolomite, siderite  0-30 3-50 9.5-18 53 Feldspars 7  0-4 5.2-8.8 2 Pyrite  5 5-13 1-2.6 4 Phosphate, gypsum,  Apatite       trace Trace trace 1 Mica  0 5-30 trace Trace TOC 0.36-9.7 0.3-11 0.4-3.1 3-7

Notes: aAfter Bruner and Smosna, 2011; bAfter Sarker and Batzle, 2010; cCompany Data

Table 1: Typical mineral composition for studied shales.