ikaruz
off to a rocking start
Member since April 2018
Posts: 4
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Post by ikaruz on Apr 24, 2018 2:58:01 GMT -5
hello everyone, can someone help me identify this rocks? i find sometimes small rocks, big rocks, but i dont know what they are. thanks
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Post by fernwood on Apr 24, 2018 4:33:14 GMT -5
Look like concretions to me. In what area did you find them?
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ikaruz
off to a rocking start
Member since April 2018
Posts: 4
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Post by ikaruz on Apr 24, 2018 5:28:56 GMT -5
hello, it was found in the mountain, but they appear at different spots with a lot of km's between them.
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Post by fernwood on Apr 24, 2018 5:46:34 GMT -5
What country/State? Do you have a closer photo of the split one? Wet and dry? The formation in the center, plus the outer appearance of some look like the concretions found at the Mazon Creek Fossil Beds in Illinois.
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ikaruz
off to a rocking start
Member since April 2018
Posts: 4
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Post by ikaruz on Apr 24, 2018 6:45:15 GMT -5
It was found in the south of portugal. There are some areas where i found some fossils. I dont remember if there are some fossils at the area where i saw this rocks.
The fossils are from spots where there was the ocean in the past
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Post by vegasjames on Apr 24, 2018 6:50:10 GMT -5
Welcome to the forum
Looks like it could be limestone. Does it react to an acid like vinegar? How hard is it? You can find Moh's hardness scales online to get ideas of what to test hardness with.
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Post by pauls on Apr 25, 2018 13:13:13 GMT -5
They look like concretions to me too.
They are caused when something in the rock breaks down and the dissolved fluids bind the grains of rock together making it harder or more resistant to weathering.
All sorts of things can cause it to happen, here's a few examples. Sometimes fossils, shells, bones etc leach Calcium and stick the sand together. Sometimes minerals, crystals of Pyrite in the rock break down and the iron cements the grains together. Sometimes organic, tree roots can rot and the acids from the wood dissolve Calcium, this is common in beach dunes. Sometimes just rainwater running to a depression in the dunes and soaking in dissolves minerals and cements things together.
Look closely at the centre of the broken one and you may be able to see the remains or a cavity left by whatever caused it.
Good luck with your rock collecting.
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ikaruz
off to a rocking start
Member since April 2018
Posts: 4
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Post by ikaruz on May 5, 2018 14:10:29 GMT -5
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Post by fernwood on May 5, 2018 14:39:59 GMT -5
Interesting.
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