my aunt and uncle live in Gnawbone for many years. That's in Brown County. Back in the 60s and 70s I recall them talking about gold prospecting in the area. They spoke of small diamonds also.
I think back at the turn of the century like the article speaks of, it was not uncommon for folks to be trying creeks for color.
I read a number of pamphlets about the gold and diamonds found in Indiana over the years. Virtually all of them have information about the glaciation period pushing the gold and diamond bearing strata down from the Canadian shield. Since the glaciers stopped in that vicinity, one finds the gold and diamonds in the creeks where they have washed out. The larger moraibilies and kames are the remnants of the large boulder and material pushed in front of the glaciers. Where they retreated these kames are the mounds now covered in soil after millennia of plant based decay forming soil.
Over thousands of years, rain, floodwaters and other erosion have washed gold and other valuable minerals into these creeks.
Only in the area south of where the glaciers stopped and retreated does the possibility exists to find these in a probability high enough to be remotely successful.
We have a farm in Owen County not too far from White River which a nice size creek flows through. I have often thought about the possibility of gold and or diamond in the area.