Katherinez Posted August 11, 2019 Share Posted August 11, 2019 (edited) Found this today on the beach in Corolla NC. Fossil? Rock? As always, I am intrigued! Edited August 11, 2019 by Katherinez Link to comment Share on other sites More sharing options...
Pemphix Posted August 11, 2019 Share Posted August 11, 2019 IMO water worn rock... Link to comment Share on other sites More sharing options...
Jackson g Posted August 11, 2019 Share Posted August 11, 2019 2 hours ago, Pemphix said: IMO water worn rock... I would agree with Pemphix, probably an ironstone concretion. Link to comment Share on other sites More sharing options...
Katherinez Posted August 11, 2019 Author Share Posted August 11, 2019 I am trying to learn here... Why would it have two different types of "layers." One looks like bone and the other is harder and shinier. I assume this happened in the ocean... I am interested in possible age and how the whole thing came about. Thank you! Link to comment Share on other sites More sharing options...
FranzBernhard Posted August 11, 2019 Share Posted August 11, 2019 3 hours ago, Pemphix said: water worn rock... Yes, it is water-worn. The action of water brought out the two different materials within this piece rather nicely. In other words, this pieces consist of two (somewhat) different rocks. 1 hour ago, Jackson g said: probably an ironstone concretion. This does not scream ironstone concretion to me. It appears to hard, to glossy, at least to me. Can you scratch the glossy part with a knife blade? 20 minutes ago, Katherinez said: Why would it have two different types of "layers." Its a water-worn piece of a layered rock sequence. But it is very hard to tell, which rock are really involved in this piece. The glossy part looks like some dense, quartz-rich material (either quartzite, chert, but I can also not exclude vein quartz). The porous part could be a weathered sandstone, the pits probably resulting from dissolution of feldspars or carbonates. But it can be also some kind of schist or even highly weathered gneiss. So, I am not even sure, if your piece consists of sedimentary rocks or metamorphic rocks. What is usually found in your area? A little bit strange is the dark color. In my area, I have found smooth, nearly black quartz pebbles up to 20 cm across. The black colour is only a very thin surface coating and the pebbles where found in a slow-flowing, small creek and are reworked from older sediment. The coloration comes from lying in the creek. Did you find your piece in a quiet area of the beach, maybe even above the high-water-mark? Would you mind snapping of a small piece of the glossy part? 33 minutes ago, Katherinez said: interested in possible age Maybe we are able to say something about that, if we know what it really is and if we also know the regional geology. Franz Bernhard Link to comment Share on other sites More sharing options...
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