Hey there! I'm happy to help!
In the word hydraulic, you can see hydr-, which is part of the prefix hydro, which means water. That is a great way to remember what hydraulic mining is.
Hydraulic mining is when you use jets of water with tons of pressure to break down rocks when mining. This allowed for larger mining operations because the water did most of the work; the only labor the people had to do was deal with the water. They didn't have to take days picking at the rocks searching for stuff. This hydraulic mining allowed them to expose more minerals quicker because it broke down rocks so quickly.
Have a wonderful day! :D
