Not sure if Greek mythology mixes in there. Miners here were usually pretty Christian, at least the higher ups that had something to say how buildings get decorated. But there was also a strong mix of different cultures and religions among them so it might have some influences from there.
The text on the shield is a miners greeting that was very common in this region. "Glück" means luck and "auf" is up, so essentially when greeting each others they tell each other good luck getting up and out of the shafts again.
Thanks for translating the shield. The New Testament of the Bible was written in Greek. There is a mention about some of the fallen angels being locked away in Tartarus. So, it's a Christain concept using Greek words to describe the place rather than an actual mythological reference. I hope that made sense. This post and your comments have been very enlightening!