A bal maiden, from the Cornish languagebal (mine) and the English maiden (young or unmarried woman), was a female manual labourer in the mining industries of Cornwall and the bordering areas of western Devon, at the south-western extremity of Great Britain. A boom in Cornish mining in the late 17th and early 18th centuries resulted in increasing numbers of women and girls were recruited to the area's mines from about 1720 to the 1770s, processing the ore sent up by the male miners underground.
With the rise of the Industrial Revolution, women and girls were again recruited in large numbers for work in ore processing. Although machinery was capable of performing much of the work done by bal maidens, the industry grew so quickly that the number of women and girls working grew steadily even though their numbers fell as a proportion of the workforce to 15–20% by 1850. At the peak of the Cornish mining boom, in around 1860, at least 6000 bal maidens were working at the region's mines. From the 1860s onward, Cornish mining went into decline In 1891 the number of bal maidens had fallen to half its peak, and by the outbreak of the First World War in 1914 very few remained in employment. In 1921 Dolcoath, the last mine to employ bal maidens, ceased operations, bringing the tradition to an end.