Donald B Wagner, an expert in ancient Chinese metallurgy, notes that attempts to trace the history of ironsand in China end with inconclusive results. One source may indicate its use as early as the Tang Dynasty (~ 700--900 AD) while others seem to contradict this interpretation. Due to wars, invasions, famines, distrust of the government, overpopulation, a rising opium epidemic, and clashes between various "tongs" of miners, very little information exists about the industry between the 11th and 19th centuries, until a European miner named Felix Tegengren arrived to find the Chinese industry in shambles. Tegengren notes that ironsand was sluice mined in Henan and Fujian by local farmers and smelted over charcoal fires to make tools, but it involved a lot of work thus was very expensive. It was only smelted where there was enough wood for the fires and cheaper steel was not readily available. Therefore, the material was considered to be economically unimportant in China. However, because the mining was safe, outdoor work, it was practiced by local farmers to supplement their income wherever it was available; in the 19th century 1000 pounds of sluiced sand typically sold for the equivalent of 50 to 60 US dollars (by 2016 exchange rates ~ 900--1000 dollars or 700--800 euros).