George A. Darling received his schooling in England and Scotland, and studied at Heidelberg (Germany), Edinburgh, Glasgow, and London. He came to Johannesburg as an assayer in 1889 and joined the South African Metallurgical Company for a year. At about this time the Cassel Gold Extracting Company of Glasgow, represented by Mr Alfred James*, erected a small plant at Salisbury Mine, Johannesburg, to investigate the recovery of gold by means of the MacArthur-Forrest cyanide process. Small amounts of tailings from various mines were treated more or less successfully, but the commercial success of the process was still in doubt. Darling experimented with this plant for some six weeks, after which he was appointed manager of the first commercial cyanide plant to be erected on the Witwatersrand, by the African Gold Recovery Syndicate of Barberton. The plant was at the Robinson Mine, belonging to the Robinson Gold Mining Company. The syndicate had obtained the right to use the process in the South African Republic, where it had been patented by the Glasgow inventors, chemist John MacArthur and the brothers Robert and William Forrest, both medical men.
Darling started treating some ten thousand tons of tailings in December 1890. He proved the process to be a commercial success, and is credited with being the first person to have done so. The Robinson Gold Mining Company then bought the plant, retaining Darling as cyanide manager. He stayed in this post for thirteen years. Within a very short time cyanide works became general on the Witwatersrand. The gold mining industry of the Transvaal was revolutionised and placed on a firm footing. In 1905 Darling held an appointment as chemist and cyanide manager at Lisbon, Berlin, Ltd, near Pilgrim's Rest, Mpumalanga.
Darling was a member of the Institution of Mining and Metallurgy (London). He was a member of the South African Association of Engineers and Architects in 1894, but not for long. By 1895 he had joined the Chemical and Metallurtical Society of South Africa (from 1902 the Chemical, Metallurgical and Mining Society of South Africa), serving on its council from 1895 to 1897, and again from 1899 to 1903. In the latter year he also briefly joined the South African Association for the Advancement of Science.
He is presumably the same person as George Darling who wrote A volunteer's letters. A record of service, 1900-1, in the South African War, which was published in Scotland in 1902. He was married to Ellen Jessie Darling, but had no children.