Bastiaan Willem Begeer, son of Willem Begeer and his wife Geertruida Vriend, was first assayer at the State Mint of the South African Republic in Pretoria. In 1898, when he no longer held this post, he published a book, The metallurgy of gold on 'The Rand'. A practical treatise on the metallurgical processes in use in the Transvaal, being a description of assaying, milling, cyaniding, refining and coining (Freiberg, 1898, 143p). By September 1899 he was an associate of the Chemical and Metallurgical Society of South Africa. He was still listed as an associate of the renamed Chemical, Metallurgical and Mining Society of South Africa after the Anglo-Boer War (1899-1902), in December 1903.
By 1901 Begeer was living in Florence, Colorado, in the United States. In October that year he applied for a patent for an improved cyaniding process of extracting precious metals from ores. The patent (US 694521) was registered in May 1902. In 1909, then residing at Mill Valley, California, he became a naturalised United States citizen. He married Anna Margaretha Coster in December 1894.