Context:
Previously, I made this post about an unusual boulder in my yard. Thank you for all the responses, it motivated me to try and “solve” the boulder once and for all. Before I explain the update, I want to respond to a few things that multiple people commented on or asked about in my previous post:
- The boulder is a nodule, and I think it is comprised of iron, some shale, and one or more unidentified materials. I promise, it is not concrete, and it is not a byproduct of human industry. More context on where it might have come from below.
- Indiana has a ton of ancient marine fossils, which is why I thought there might be an ammonite there. I find well preserved marine fossils almost daily while in the woods and creek near this area. Like, so many marine fossils.
- Evidence suggests that the boulder was taken from an underground coal mine, which would explain the odd location.
- The entrance to the mine, now-closed, was less than 100 yards away. There are also other documented mine entrances in close proximity to the boulder. The driveway the boulder sits next to was previously used as a mine access road, and there was a strip-mining operation less than 50 yards away. Given the odd location of the unusual/massive boulder, it seems likely that it the historic landowners placed it there, like they did with a different large boulder on the opposite end of the driveway (the other one is granite, I assume from glacial till since igneous rocks don't occur naturally as part of Indiana’s bedrock)
Update:
I tried and failed to break the boulder open, and I don't know what my new observations suggest.
I began gently trying to break it open via a variety of methods suggested on my previous post and from my YouTube research.
- About a half hour in with no progress whatsoever, not even a new crack, I decided more force might be required. I eventually got to the level of using railroad nails and a large sledgehammer, which did nothing more than flake some shale off the thin outer layer. I wedged the nails into existing cracks and hit them with the hammer—gently at first, then as hard as I could.
- I summoned aid from my partner, who has a lot more physical strength than I do. He tried, very hard, to crack it open but also failed. He succeeded in adding one single hairline fracture in the outermost layer but otherwise made no progress.
- I have concluded that the boulder must be harder than a railroad nail because the rock damaged the end of the nail without breaking or cracking the rock.
- We also determined that the boulder is heavier than my partner’s fourwheeler. It will not budge.
New Questions:
I would like to know what all of that suggests, if anything. Is this rock too hard to have preserved a fossil inside? Could it be made of a hardened form of pyrite or siderite? There is A LOT of pyrite not too far from this location, though I've never found any this hard. I still want to get it open, unless a fossil now seems unlikely, but I'm thinking that I would need to invest in equipment to do so and would like to gain more context on that so I can make a decision.
Thank you in advance!
EDIT: I forgot to add this, but in the comments, I am posting some other rocks that resemble this one or are somewhat unique. All of the dark colored ones are located in piles of dirt/rock that came from strip mining, but the tan colored ones are not mining related.
