A gunpowder factory established in 1844 by George Frean, and remained in use until 1897, when it closed as a result of increasing competition from dynamite and a slump in local mining activity. The production of gunpowder involved combining a mixture of saltpetre, sulphur and charcoal and the buildings in which the different stages of the process were carried out survive at Powder Mills. The process was inherently dangerous and to reduce the chances of cataclysmic explosions, the buildings were situated at a safe distance from each other and each had a flimsy roof which would have allowed any explosion to be carried upwards. Amongst the buildings identified at Powder Mills are: grinding mills; blending mills; incorporating mills; a range of buildings where the gunpowder was broken, pressed, corned, dried, dusted and glazed; and finally charge magazines. The quality of the finished gunpowder was tested using two different techniques. At SX 6377681 a proving mortar, which was used to test the strength of the gunpowder, still sits on a restored carriage. Whilst at SX 62757750 a number of large boulders have been split using a single charge, possibly the result of testing. Within the vicinity of the gunpowder works there are four quarries from which material was derived during the construction of the buildings. Scheduled.