100 Francs CFA Earth Tektite

Tektites are natural glass formed by meteorite impacts, and the specimen embedded in this coin almost certainly originated from one of four recognized strewn fields — most likely the Australasian field, the largest on Earth, which stretches across Southeast Asia and southern Australia and dates to roughly 790,000 years ago. The Republic of the Congo issued this piece through a licensing arrangement common among small sovereign issuers who use numismatic novelty output as a minor revenue stream, with no meaningful domestic circulation intended.