Firedamp is explosive at concentrations between 4% and 16%, with most explosions occurring at around 10%. It caused many deaths in coal mines before the invention of the Geordie lamp and Davy lamp. Even after the safety lamps were brought into common use, firedamp explosions could still occur from sparks produced when coal contaminated with pyrites was struck with metal tools. The presence of coal dust in the air increased the risk of explosion with firedamp, and could cause explosions even in the absence of firedamp. The Tyneside coal mines in England had the deadly combination of bituminous coal contaminated with pyrites, and there were a great number of deaths due to accidents caused by firedamp explosions, including 102 dead at Wallsend in 1835.