FMF - Friends of Minerals Forum, discussion and message board

[icycatelf]

Found this interesting rock a couple days ago. Someone on a Facebook group told me that it was a really weathered garnet schist. I found a few other posts online that do look very similar to mine, but I wanted to get some more opinions. I'd rather not break it and risk getting nothing out of it.

[kushmeja]

Looks more like a homogenous rock / mineral to me from your pics, and I'm not seeing any mica or garnet either. Although eroded garnets in schist would have a similar surface texture, you would see the individual garnet crystals protruding from the matrix if that were the case. My guess would be some sort of Limonite concretion or pseudomorph possibly.

If you could tell us the general area where you found it, or do some basic tests like hardness or streak, you would have a much better chance of getting a more accurate ID.

[Bob Carnein]

It isn't likely that garnet schist would be native to Kentucky, but it could be a glacial erratic (did you find it in northern KY?). I agree with Kushmeja; to me the "lumps" look like concretions in a sedimentary rock.

[icycatelf]

I was thinking concretions/nodules too. Lots of iron-oxide concretions/nodules here. And the rock seems more sedimentary than metamorphic. Like sandstone with some iron mixed in. There are mica flakes though, or at least what I was always taught were mica flakes. They look like glitter.

It was found in eastern KY, between the Hyden and Pikeville formations. I've also found lycopod fossils there, but nothing particularly crystal-y.

[kushmeja]

I'd go with limonite concretion then. I find stuff like this where I hunt for fossils shark teeth by Holmdel, NJ. They have a wide variety of shapes & slightly varied composition, so they sometimes look like fossils or native artifacts even.

it could possibly be some sort of fossil (tree bark possibly?) that formed from a limonite rich sediment too. We have tree fossils up by me in the old coal dumps that have a similar texture that are fossils from the bark of trees. Just a wild guess as to it possibly being a fossil though.

[Pete Modreski]

This illustrates the difficulty in identifying or recognizing what's in a rock, just from photos!

When you examine your rock close up--if the matrix looks like uniform, sandy particles, that it probably is a sandstone with iron oxide nodules.

If it were a garnet schist (which it does, admittedly, sort of look like, in the photos), the matrix would be obviously a mix of sparkly crystals, some of which should be recognizable as mica flakes, and if the blobs were garnet, they would be quite hard.

[Riccardo Modanesi]

Hi to everybody!
I don't know the territory of Kentucky, but I wouldn't exclude this specimen is a fossil.
Greetings from Italy by Riccardo.

[icycatelf]

Posted on a fossil forum. The "warts" are too random to be any kind of bark fossil.

Here's a close-up of the side if that helps with anything.