Hello & Please identify this rock

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Offline CanopicJar

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Hello & Please identify this rock
« on: 01/11/2010 00:34:50 »
I found this rock on vacation and had to bring it back with me!  What is it?

Thanks,

Travis





« Last Edit: 01/11/2010 00:37:43 by CanopicJar »

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Offline RD

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Hello & Please identify this rock
« Reply #1 on: 01/11/2010 01:40:30 »
Possibly grey outer layer is "vesicular basalt"  [?]
the holes (vesicles) are caused by gas bubbles when the basalt was molten.

The basalt has coated another type rock so is a "basaltic intrusion"  [?]

[ [?] these are uneducated guesses, but may be of help]
« Last Edit: 01/11/2010 01:53:59 by RD »

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Offline Bass

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Hello & Please identify this rock
« Reply #2 on: 01/11/2010 15:38:47 »
My guess is some sort of concretion in limestone?  Can you scratch the outer rind with a knife?
Old enough to have a grandson
Slow enough to study rocks
Thirsty enough to find a pub

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Offline CanopicJar

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Hello & Please identify this rock
« Reply #3 on: 01/11/2010 17:42:41 »
It does not seem to scratch with a flat blade from my multi-tool.

Here are some additional shots.







FYI, this rock was found on the Slate Islands, which were apparently created from a meteor impact.  It is also home to the world's largest shatter cone:





and...



Travis

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Offline RD

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Hello & Please identify this rock
« Reply #4 on: 01/11/2010 18:46:58 »


This bulls-eye mark may have been made by a limpet.
« Last Edit: 01/11/2010 18:51:01 by RD »

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Offline Bass

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Hello & Please identify this rock
« Reply #5 on: 02/11/2010 00:26:48 »
In that case, I suspect the rock may be psuedotachylite (interior is an impact breccia clast).

Nice photos, by the way.
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Offline RD

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Hello & Please identify this rock
« Reply #6 on: 02/11/2010 00:52:52 »
Bigger vesicles in cross section...

[attachment=13320]

http://mountainbeltway.wordpress.com/2010/04/09/holey-basalt/
« Last Edit: 02/11/2010 01:03:21 by RD »

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Offline CanopicJar

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Hello & Please identify this rock
« Reply #7 on: 02/11/2010 01:18:10 »
Thanks for the help!  The trip to the Slate Islands was an amazing trip.  Every time you turned a corner on the beach, you ran into different types of rocks.