 Sapphires were first documented in Anosy by Étienne de Flacourt in 1658, and were described by a French geologist working in the mica mines near Tranomaro in the 1950s.High-quality blue sapphires of up to were found near the village of Andranondambo in 1991, and in the mid-1990s briefly attracted a rush of almost 10,000 miners.A 2004 environmental impact study found the area "highly degraded" with threatened ecosystems.