During the quest “City of the Sun” in Atlas Fallen, you will gain access to the mines and while here, you will need to “Search the mine for sources of Corruption”. Having done a few loops of the mine and gotten lost as to what I was supposed to be looking for, I finally figured it out, here is what you need to do.
Finding The Source of Corruption
As you explore the mine, you will find many different areas where there are several cracked areas on the ground with the blue glow where you can use the raise ability. Most of them are going to reveal junk and nothing of use, which may stop you from wanting to use them.
You need to head around three-quarters of the way down into the mine and you will find a stone structure. Use the raise ability on the cracks on the ground nearby and one of them will reveal an unusual item which will be the source of the corruption that you are looking for. The image below will show you the exact location where I found the item.