Born in the Algerian port of Oran in November 1881, Gaston Ripert joined the French army in 1904. He served in the French colonies and was made a chevalier of the Légion d'honneur in 1912.

After he left the army, Ripert, a multi-linguist, became a colonial administrator in the Ivory Coast just before World War I, but was called up to fight in 1914. After being wounded twice, he was sent back to Africa as a diplomat, this time to Mauritania where he 'discovered' the Chinguetti meteorite in 1916. He was an avid collector of fossils and other geological specimens, and many of his finds were accepted by French museums.

A year later, he was posted to Cameroon, and he ended up running a coffee plantation there. He wrote to Théodore Monod in 1934: 'I know that the general opinion is that the stone does not exist; that to some, I am purely and simply an impostor who picked up a metallic specimen … that to others, I am a simpleton who mistook a sandstone outcrop … for an enormous meteorite. I shall do nothing to disabuse them … I know only what I saw.'

Dr Jean Bosler, director of the Le Verrier Observatory in Marseilles, wrote of him in the 1930s that he was 'a calm, serious and modest man', well acquainted with geology. During World War II, Ripert served as a major at the garrison at Toulon in France. He died in December 1957.

Théodore Monod

Professor Théodore Monod (born 1902) was - at the age of 97 - still working at the Musée National d'Histoire Naturelle in Paris when the Channel 4 programme on the Chinguetti meteorite was being made.

Educated at the Sorbonne, he made extensive botanical and geological studies of remote regions of the Sahara. His most memorable trans-Saharan crossing of 560 miles was by camel from Wadan in Mauritania to Arawan in Mali, made by laying down advance depots of food and water. He subsequently became director of the Institut Français d'Afrique Noire (1938-64) and dean of the faculty of sciences of Dakar University in Senegal.

An expert on fossil fish, and with intimate knowledge of Mauritania and desert lore, his hunt for the Chinguetti meteorite began in 1934 when he agreed to make enquiries about Ripert's alleged discovery. Despite various searches over the years, Monod concluded in 1989 that Ripert had been mistaken: 'An error was made in the identification of the rock of a 40-metre [130 foot] hill that is entirely sedimentary with no trace of metal,' he wrote.

Jacques Gallouédec

Former French air force officer Jacques Gallouédec was carrying out aerial surveys for the Mauritanian water authority when, in 1980, he spotted a strange semi-circular ground formation to the south-east of Chinguetti. He sent details to Théodore Monod but the professor was unable to locate it. Gallouédec lives in the Mauritanian capital, Nouakchott. He is the only person alive today who claims to have seen Ripert's rock.