Ali Somarin wrote:

"Pyrite is found in a wide variety of geological settings, from igneous, sedimentary and metamorphic rock to hydrothermal mineral deposits, as well as in coal beds and as a replacement mineral in fossils. Pyrite can be either disseminated throughout igneous rock or concentrated in layers, depending on depositional mechanism and environment. Pyrite forms in sedimentary rocks in oxygen-poor environments in the presence of iron and sulfur. These are usually organic environments, such as coal and black shale, where decaying organic material consumes oxygen and releases sulfur. Pyrite often replaces plant debris and shells to create pyrite fossils or flattened discs called pyrite dollars."

https://www.thermofisher.com/blog/mining/pyrite-the-real-story-behind-fools-gold/

You should know also the origin of sulfur in coal to give you a wide views

Sulfur in coals: A review of geochemistry and origins-

LinChou 2012

Article Sulfur in coals: A review of geochemistry and origins

Dear Mr. Maurya,

Pyrite and chalcopyrite are the most common Fe and Cu sulfides and particularly widespread in almost all reducing environments, but mainly of subeconomic grade or accessory minerals. It is the abundance in their abundance in the crusts and the strongly reducing regime. If their emplacement is truly diagenetic in the course of coalification or induced by hydrothermal or magmatic processes can only be decided based on more advanced-level studies involving micro-chemistry and/or detailed mineralogical studies.

DILL, H. G., EBERHARD, E. and HARTMANN, B. (1997) Use of variations in unit cell lenght, reflectance and hardness determining the origin of Fe disulphides in sedimentary rocks.- Sedimentary Geology, 107: 281-301.

DILL, H.G. and PÖLLMANN, H. (2002) Chemical composition and mineral matter of paralic and limnic coal types of lignite through anthracite rank. Upper Carboniferous coal in comparison with Mesozoic and Cenozoic coals (Germany).- Canadian Society of Petroleum Geologists Memoir, 19: 851-867.

DILL, H.G., ALTANGEREL S., BULGAMAA J., HONGOR O., KHISHIGSUREN S., MAJIGSUREN Yo., MYAGMARSUREN S. and HEUNISCH C. (2004) The Baganuur Coal Deposit, Mongolia: depositional environments and paleoecology of a Lower Cretaceous coal-bearing intermontane basin in Eastern Asia. – International Journal of Coal Geology, 60: 197-236.

DILL, H.G., WEHNER, H., KUS, J., BOTZ, R., BERNER, Z., STÜBEN, D. and AL-SAYIGH A. (2007) The Eocene Rusayl Formation, Oman, carbonaceous rocks in calcareous shelf sediments: environment of deposition, alteration and hydrocarbon potential.- International Journal of Coal Geology 72: 89-123.

DILL, H.G., KUS, J., DOHRMANN, R. and TSOY, Y. (2008) Supergene and hypogene alteration in the dual-use kaolin-bearing coal deposit Angren, SE Uzbekistan.- International Journal of Coal Geology, 75: 225-240.

DILL, H.G., BECHTEL, A., KUS, J., GRATZER, R. and ABU HAMAD, A. M. B. (2010) Deposition and alteration of carbonaceous series within a Neotethyan rift at thewestern boundary of the Arabian Plate: The Late Permian Um Irna Formation, NW Jordan, a petroleum system.- International Journal of Coal Geology, 81: 1-24.

Good luck

H.G.Dill

Thank you So much Sir.

I'll go through your recommended papers