Chert is a fine-grained, flinty siliceous rock usually found in veins of limestone. It was worked into tools in prehistoric times due to the ease with which it could be shaped by chipping off flakes to produce sharp edges in a similar manner to flint, more recently chert was ground into calcined flint and used as a whitening agent in earthenware manufacture.
In this Mine 90% of the limestone has been replaced by a laminated form of chert, The chert is in two beds up to 2.4m thick the main mottled throstlebreast bed and above it the more flinty roof chert.
The popularity of chert grew and it became an in-demand stone in the mid-1700s due to to Thomas Benson who patented a new 'wet' process of grinding flint for the usage in the pottery making process. Previous grinding of flint had utilized grain-grinding millstones but this produced copious dust resulting in workers dying from silicosis. Benson's first attempt at a 'wet' process. was in 1726 using iron balls. This had the unwanted consequence of leaving deposits of iron in the pottery, hence he then replaced this with the colored granite stones and then chert which gave superior results still.
In the mid 1800 chert extraction shifted to mining which was made viable by the rising price of chert and declining transport costs, Chert production from the mine in the late 1870s and early 1880s averaged around 3,500 tons as the workings developed into an extensive system of passages with eight entrances with the help of compression Air drilling. On the 19th June 1899 53-year-old Matthew Hollis of Bakewell was killed after returning to a charge that didn’t go off, While he and two other men were setting a second charge the initial charge went off. A second fatality also followed in 1919, On 17th April the 62 year-old John Bond was killed returning to fire his 11th charge of the shift when it went off prematurely without warning.
In 1925, 41 men were employed in the mine and Derbyshire chert production peaked at 6,369 tons in 1928, By 1945 only 21 were at work with only 12 working underground and eventually closed between 1959 and 1961. In recent years, the few underground visitors to the Mine have included cave divers, using the clear subterranean waters for training purposes.
(This was a permission visit all entrances are gated locked)
In this Mine 90% of the limestone has been replaced by a laminated form of chert, The chert is in two beds up to 2.4m thick the main mottled throstlebreast bed and above it the more flinty roof chert.
The popularity of chert grew and it became an in-demand stone in the mid-1700s due to to Thomas Benson who patented a new 'wet' process of grinding flint for the usage in the pottery making process. Previous grinding of flint had utilized grain-grinding millstones but this produced copious dust resulting in workers dying from silicosis. Benson's first attempt at a 'wet' process. was in 1726 using iron balls. This had the unwanted consequence of leaving deposits of iron in the pottery, hence he then replaced this with the colored granite stones and then chert which gave superior results still.
In the mid 1800 chert extraction shifted to mining which was made viable by the rising price of chert and declining transport costs, Chert production from the mine in the late 1870s and early 1880s averaged around 3,500 tons as the workings developed into an extensive system of passages with eight entrances with the help of compression Air drilling. On the 19th June 1899 53-year-old Matthew Hollis of Bakewell was killed after returning to a charge that didn’t go off, While he and two other men were setting a second charge the initial charge went off. A second fatality also followed in 1919, On 17th April the 62 year-old John Bond was killed returning to fire his 11th charge of the shift when it went off prematurely without warning.
In 1925, 41 men were employed in the mine and Derbyshire chert production peaked at 6,369 tons in 1928, By 1945 only 21 were at work with only 12 working underground and eventually closed between 1959 and 1961. In recent years, the few underground visitors to the Mine have included cave divers, using the clear subterranean waters for training purposes.
(This was a permission visit all entrances are gated locked)
