Textural Studies on the Ores of Amjhore Pyrite Deposit, Rohtas District, Bihar, India

The pyrite ore body at Amjhore occurs as a horizontal to sub-horizontal 'bed' composed, in part, of a hard massive variety and, in part, of a more friable disseminated variety of ore. Microscopic studies reveal that the disseminated ore is made up chiefly of large spherules of pyrite (100,.μm to 1200,.μm in dia.) in a matrix of shale containing also dispersed subhedral toeuhedral pyrite (4,.μm to 30 μm in size). Occasionally, large isolated hexahedral grains of pyrite are also present in the disseminated ores. The microscopic studies indicate development of pyrite spherules from initially close-spaced growth nuclei (perhaps of the precursor-mineral pyrite). The spherules and hexahedra of pyrite fuse together to give fise to the massive variety of ore which show such textures on etching. The textural studies alone cannot, however. be used to infer the exact genesis of the deposit.