Petrila is located on the Jiul de Est river (Eastern Schil), between the Șureanu mountains in the north and the Parâng mountains in the south.
Petrila experienced a significant boom after significant coal deposits were discovered in the 18th century and a mine opened in Petrila in 1859. Mining was the city's most important industry from the last third of the 19th century and throughout the 20th century. At times, 5,000 miners worked in the Petrila mine. The highest annual production was reached in 1983 with 1.2 million tons of coal.[3]
When the Romanian state began to reduce its mining subsidies with the gradual transition to a market economy after 1990, production in Petrila also fell drastically; in 2014 it was still 110,000 tons. On November 15, 2008, two explosions occurred in the Petrila mine, which claimed a total of 13 lives.[4] The Petrila mine was closed at the end of October 2015. At the end of the day, about 300 miners were still employed there.