Shales, carbonaceous matter

There are two possibilities here to explain this correlation. One is that isotopically heavy sulfide sulfur derived from seawater sulfate was fixed in shale because reducing agency of shale with carbonaceous matters is thought to be stronger than that of sandstone. The ore fluids extracted this sulfur. Gold of low NAg precipitated in shale like the Kuryu deposit under more reducing environment than in sandstone like the Saigane deposit. 

If the mineral matter in the coal exceeds about 40%, then the material is referred to as a coaly or carbonaceous shale. If the mineral matter is a finely divided clay, well dispersed in the coal, then the material may be described as a stony coal or bone coal. 

As regards the Chirmiri areas from where the two seams have been collected, Fermor (8) considered the most important exposure as that at the waterfall known as Karar Khoh in the Korea nala, where 36 feet of coal in seven beds occur in 48 feet of strata. The coal seams are underlain and over-lain by coarse to medium grained sandstones and black carbonaceous shales. Seam 2 is at the top of the section while Seam 4 is below. The two seams are separated by 40 feet. Seam 2 is 4 feet thick, while Seam 4 is actually 12 feet thick, but in the mines the mined portion is only 6 feet thick. Pillar columns were collected from these two seams for the present investigation they form the subject matter of this paper. 

Finally, impure coal is that coal which contains between 25% and 50% w/w ash (after ignition) on a dry basis. Two types of impure coal are bone coal and mineralized coal. The former (bone coal) contains clay or other fine-grained mineral matter and, moreover, if the bone coal contains more than 50% w/w of ash, it is often (and properly) termed carbonaceous shale or siltstone. Mineralized coal is impure coal which is heavily impregnated with mineral matter. The inorganic material can be dispersed and/or localized along fissures or cleat joints (Law, 1993 Laubach et al., 1998). 

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