Naked Science Forum
Non Life Sciences => Geology, Palaeontology & Archaeology => Topic started by: CanopicJar on 01/11/2010 00:34:50
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I found this rock on vacation and had to bring it back with me! What is it?
Thanks,
Travis
(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fhome.fuse.net%2FCanopicJar%2FIMG_0524.JPG&hash=420dc64b90fc4ce1c444268ee660b6bf)
(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fhome.fuse.net%2FCanopicJar%2FIMG_0525.JPG&hash=579fa0fad9cf4eb9e6efb5c92a87999a)
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Possibly grey outer layer is "vesicular basalt (http://www.pitt.edu/~cejones/GeoImages/2IgneousRocks/IgneousTextures/7VesicularAmygdaloidal.html)" [?]
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]
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My guess is some sort of concretion in limestone? Can you scratch the outer rind with a knife?
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It does not seem to scratch with a flat blade from my multi-tool.
Here are some additional shots.
(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fhome.fuse.net%2FCanopicJar%2FIMG_1223a.JPG&hash=ad24108a82963b5967b6900e8958b311)
(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fhome.fuse.net%2FCanopicJar%2FIMG_1224a.JPG&hash=22fa3b6e9e244b454b839d1dabe1818e)
(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fhome.fuse.net%2FCanopicJar%2FIMG_1225a.JPG&hash=6d6b92915122440d75cfb59a39deeedb)
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:
(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fhome.fuse.net%2FCanopicJar%2FIMG_8201.JPG&hash=d7b1f0fd92272c8e0c78294b9ba38be5)
(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fhome.fuse.net%2FCanopicJar%2FIMG_8202.JPG&hash=a1fa2627167cd40381c61ad97bd639cc)
and...
(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fhome.fuse.net%2FCanopicJar%2FIMG_8139.JPG&hash=9fa05dd7b137b28eed1136f3e4b73d02)
Travis
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(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fhome.fuse.net%2FCanopicJar%2FIMG_1223a.JPG&hash=ad24108a82963b5967b6900e8958b311)
This bulls-eye mark may have been made by a limpet (http://www.theseashore.org.uk/theseashore/Resources%20for%20seashoreweb/Images%20for%20New%20Pages/Limpets%20&%20scars.jpg).
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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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Bigger vesicles in cross section...
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http://mountainbeltway.wordpress.com/2010/04/09/holey-basalt/
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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.