fancy concrete? SOLVED

[RJo]

Ok... so it's not fancy concrete. It appears to be a composite of some sort. At this point, everyone should already know that I'm not a geologist. On top of that, this is my first post here. I'm aware of the various hardness scales, streak tests, etc. but that's about it. I don't have any ID kits... yet.

I actually found this beast of a specimen while deer hunting (between snowfalls). I have a terrible habit of staring at the ground and examining anything odd in front of my feet as I creep along--terrible for my venison supply, but not so terrible for my arrowhead collection. In any event, the rock was protruding out of the crest of what I can only describe as an earthen moraine dotted on the surface with large round granite boulders.

After some reading in a 1957 Rocks and Minerals field guide, I thought I had a good lead on the rock's ID. The black is similar to black flint (chert?), which isn't too difficult to find here. However, the fractured edges don't show the knap-like effect that flint arrowheads and flint chips show. Looking at some other sedimentary rocks in the guide, chalcedony looks like a dead ringer--only problem is... I'm reading all over the web that naturally black chalcedony is so rare that it might as well not exist. To further confuse me, the commercial gemstone industry refers to it as black onyx and most black onyx is artificially dyed.

I understand that impure translucent chalcedony can fill cracks, which also seems to fit this specimen. In the attached images, I zoomed in on on an elliptical ball of this stuff protruding from one of the rock's edges. I also believe that the rock contains metals. When I picked the rock, the off white color in the small end was covered with a dry white film (aluminum?), and the gray color was covered with a dry blue-green film (zinc?). I read that these 2 common metals can fill the voids in metamorphosized sedimentary rock. What I don't get is... how sediment can be heated, pressurized, and returned to the surface of the earth.

What was the buried side of the rock is covered with surface rust, so obviously there's some iron. However, the rock is not magnetic when a neomydium magnet is applied. There are some small triangular "light gold" flecks sparsely placed (corundum?). Apparently, this a "super strength aluminum" which would tend to jibe. The 2 pics showing a faint green color are end shots of the large end. It's tough to photograph, but there is a bit of a washboard formation with triangular ridges running vertically in those 2 pics. The rock is 14" at its longest dimension, and 29.8 lbs. {[(me + the rock) - me] on a digital bathroom scale}.

A few notes: There are some odd things on the surface here (Sussex County, NJ)--most notably, a sky blue ball bigger than me with white swirled into it. It has even larger bubbles. Franklin(Franklinite), NJ is maybe 25 minutes away, driving. There is an old Lenni Lenape village site that I can hike to, but anything I've found has been a 1/4 mile or so away from it.

Thanks in advance to all who can confirm or correct what I've posted. Any info is appreciated. Happy hounding.

Ryan

 

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[RJo]

Update... A kind soul politely directed me toward polymict ureilite meteorites at Meteorite.fr - Classification - Stony Meteorites - Primitive Achondrites. I was way off the mark.

 

[Eu_citzen]

Mica schist with garnets seems way more likely.

 

[Turkısh Man]

Peridotite igneous rocs,%30 Olivine,%10 plajioklas.

 

[RJo]

Mica schist with garnets seems way more likely.

Peridotite igneous rocs,%30 Olivine,%10 plajioklas.

Thank you very much, guys. I'll read up on all 5. Either of these would be a pleasant surprise. My fiance has suggested we bring it along to the Franklin Mineral Museum. Ashamed to say, I've never visited. Maybe they'd like to retain a chunk of it. I bet it would look nice cross cut through one of the veins.

 

[RJo]

@mods, please mark solved thanks to Turkish Man's reply.

 

[Eu_citzen]

Did you get a positive ID? It doesn't look like any peridotite I ever saw. They tend to be greenish to blackish.

 

[Jim in Idaho]

Just looks like some sort of igneous breccia to me. It's always hard to tell from pics.
Jim