Snoman;
Coal mines are extra dangerous, you could not be more right about that.
Dangerous even to the point that they made special bronze hammers and wrenches for them to prevent sparking.
There is a reason Davy Lamps were invented and why Mine Rescue often wear a pin representing one.

Different mines are different, but they are all dirty, wet, cold and very dangerous places to work.

When you do visit your grandfather's grave you be sure to carry a blessing for him from me too.