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<br />early in tl,e hl story of coal d7agenesie by bacterial reduction of sulfate and ferrous iron <br />' 1n order to netaholize the organic compounds presents. (In this di acusal ort, the name <br />"pyrite" will be used to indicate hoth pyrtte'and marcaaitaJ. It is apparently in this <br />setting that franboldal pyrite forms (Caruccio and others, 1977). Frambotdal pyrite, to <br />tamprtsed of submf Cron-sized crystals of pyrite. Studt ea by Caruccio (Caruccio and <br />Part zek, 1967; Caruccio, 1968: Caruccio, 7970; Caruccio and Cei del, 1982) have sham that <br />framboidal pyrite is reaponsi ble for the production of acid, while ether forms (mascive, <br />plant replacenant, primary euhadral antl secondary ci eat filling) do not react rapidly <br />enough to produce substantial acid. ACCOrdi ng io Caruccio aM others (7977), the <br />occurrence of framhoidal pyrite is rol sled to dapoai tf onal anvi ronmant. It is found more <br />commonly in near marine (back bay and lower delta plain) than in upper dolts plain <br />envi romaents. The second important factor in the productt on of acid is the presence or <br />absence oT carbonate mi nerais in racks asaoci sled wiN the pyrite. <br />OifTerent laboratory techniques have bean used for predtcti ng the potential for aeftl <br />generalfon, and result In a va7 ue termed the "Ac td Beae Potential" or ABP, In order to <br />measure or ealcut ate the potentf al acidity vi thar (1) the py ri to (plus organic sulfur, Tn <br />same techniques) content is measured, and potential eeidity is calculated, ar (2) a sample <br />• is oxidized with hydrogen peroxide (attar treating with acid to remove carbonates and <br />gypsum, and rinsing) and the amount of acid produced 1s measured 6y titration. Tha <br />neutralization potential fn measured by titration, and to indlcatl ve of the content of <br />alkaline carbonates, exchargeabte bases, and readily weatherable ail ieates. These ino <br />meaauremenes are expressed in terns of equi valent~ CaC03. The ABP is calculated 6y <br />subtracting the potnnti al acidity fray the neutralization potential. If the ABP Is <br />positive, reactions of Ue overburden with water are likely to yield pH's greater than 7. <br />A negative ABP Tndi eataa that ecidia conditions may develop. <br />An important assumption in this approach Sa that all the pyrite present to reactive. When <br />the acid potential is determined by oxidation wS tb hydrogen peroxide, the use of elevated <br />temperatures encourages oxidation of the non-framboidal pyrite. Smith and others (1974, <br />p. 48) discuss the exeell enE agreement Defxresn potenii el aci tli ty determined by oxidation <br />and that cetculatad from total pyri to content, which indf cater that pyrite ozi data on <br />during the laboratory procedure is complete, or nearly so. Hence, the potential aefdity <br />pareneter overestimates the amount of said that might be produced because non-tranibol dal <br />forms of pyrite era oxi dl zed in addi tl on to the other forms. <br />17-39 Reef red 04/11/88 <br />• <br />REVISED MARCH 2006 Attachment 2.05.6(3x2-47 <br />