The phrase "rib of coal" doesn't have a standard recognized meaning in English; it is likely a rare or incorrect combination of words.

कोई मानक मान्यता नहीं है; इसका अर्थ समझ से परे है

English Usage: The miner stumbled across what he described as a rib of coal buried deep in the tunnel.

Hindi Usage: खदान मजदूर ने गहरी सुरंग में दबे हुए कोयले की एक पसली जैसी चीज को खोजा।