Geology Puzzle. A rock I found in my yard

Jeff · August 05, 2009, 07:39:00 PM

No, I don't have the answer, I am hoping someone on here does. I showed this to several people at the pigroast. I found it a day or so before people started to arrive in the stones around our patio.

ANy ideas?

Jeff · August 05, 2009, 07:45:42 PM

Zoom.

beenthere · August 05, 2009, 08:41:55 PM

I'd say "not a LogRite brownie".

Hilltop366 · August 05, 2009, 10:40:06 PM

Chocolate covered almond gone bad?

or may be a petrified reptile egg?

tyb525 · August 05, 2009, 10:43:47 PM

A rock that got covered in lava at some point?

Ianab · August 06, 2009, 01:14:14 AM

I think that the white is the original rock rock thats been burried in silt for 'ages' (litterally) and has formed a 'Concretion'

It acts as a sort of seed crystal for more stone to build up around it, the same way as a stalagmite builds up. Sometimes they find dinosaur bones surrounded in the same way.

After a long enough time the surrounding silt or now mudstone gets uncovered and the two layer stone is left.

There are boulder here in NZ that have grown to about 6ft across and are now being uncovered by the sea.

Thats the theory of how they were formed anyway.

Reading up on Wikipedia link I see that similar formations are found near Lake Huron

http://en.wikipedia.org/wiki/Moeraki_Boulders
http://en.wikipedia.org/wiki/Concretions

Ian

SwampDonkey · August 06, 2009, 04:55:16 AM

That certainly looks plausible. I have a rock that is magnesium sulfate, the sulfur is/has precipitated from the rock to form a coating of sulfur all over the rock. You know it's sulfur from the smell of a fresh broken piece. Inside it looks like a chunk of shiny metal. I took and chipped off most all the sulfur precipitate.

Dana · August 20, 2009, 09:17:52 AM

Does a magnet stick to the outer layer?

Dana · August 21, 2009, 10:03:58 AM

Quote from: Dana on August 20, 2009, 09:17:52 AM
Does a magnet stick to the outer layer?

One more try here :-\ Look at the bottom of the page on the provided link.
http://www.meteoritemarket.com/metid4.htm

Jeff · August 21, 2009, 11:18:30 AM

I just checked. Its non-magnetic.

caver · October 24, 2009, 11:35:17 AM

Looks like Leverite.

Ironwood · October 24, 2009, 12:06:51 PM

Concretions are non fossil formations around what where usually air pockets, the inner material usually then percolates in either in steam (near volcanic activity) which genrates beautiful geodes or in your case non-volcanic sedimentation most likely liquiifed and not so stunning. These are VERY common but cool. We look for them in the Aldi parking lot when we're waiting for Momma to come back out from grocery shopping (Daddy wanted to be a Palentologist, Geologist) we have LOTS of fun w/ litttle ones.

Ironwood