What do you think this is?

[stdenis_jd]

it's on the exterior of a Michigan pudding stone, metamorphosed quartzite sand conglomerate - I've only seen green mineralization on one of them before and it was embedded and ID'd by a geologist as likely green fluorite. This one though appears to be malachite or some other copper mineralization...if you're able to zoom in and see the streak, it has a fibrous look to it, it isn't a smear more like a river delta zoomed way out.

Such a small sample I'm not able to get a streak test within reason and definitely not hardness either. Just wondering what you think...seems strange it could survive in this type of matrix - these rocks have been compressed and tumbled around by glaciers for several hundred million years.

 

[trdking]

looks like Malachite to me. Any copper in the vicinity?

 

[IAMZIM]

I agree with trdking, looks like Malachite.

 

[Icewing]

The area around the Great Lakes is from my understanding, very rich in copper. And it does look like oxidized copper. Have you tried scratching the green spot to see if it's copper on the inside?

 

[stdenis_jd]

Lots of copper in the western upper peninsula of MI, and this was found in the west central lower peninsula - funny thing is, mostly everything here is glacial erratic so we get stuff deposited here from all over Canada and the U.P. but these quartz/jasper conglomerates tend to come from the far eastern end of the U.P. and the copper is mostly the central to western U.P.

The two coming together after formation, during glacial movement is the only way as they would definitely not have been formed together. So yeah, pretty sure it has to be malachite/copper oxide.

@Icewing - it's just superficial, if you were to see it in person it definitely doesn't extend more than 1mm into the surface. However, if I decided to cut it (which I will probably not do since that would probably just ruin it) and found copper minerals inside it that would be a one in a billion find. I can't see it being inside the rock as possible

 

[Icewing]

No no, I mean use a small metal pick like a needle or ice pick to just scratch the oxidation if that's what it is.

 

[stdenis_jd]

yeah, I thought of using the steel dental picks I have but I've been sketchy on doing so...I think I will anyway

I'm pretty stoked to find such a rarity - I have a collection of 500+ pudding stones and never seen this before...they say corundum is occasionally found in them too which would be cool to find! Being a conglomerate it's theoretically possible to find almost anything embedded in them