Dilla1080 1 Posted December 31, 2020 Share Posted December 31, 2020 Hello! I am new to this forum and new to the world of identifying rocks and fossils. I have several rocks and fossils that I am trying to identify on my own, but this one is proving to be beyond my VERY limited knowledge. My grandfather and I would go rock hunting in the Texas hill country when I was a little girl. He recently passed away and I am now slowly moving all of his rocks that he collected throughout his life to my home. Unfortunately, I do not know much about this rock. I ASSUME he acquired it in the Texas hill country but I am not certain. The rock is VERY heavy, especially for its size, probably 80-100 lbs and is approximately 17" wide and 4.5" deep. It has a reddish-brown color with black markings throughout. On one side there are "swirl" or "circular" markings and the edges appear to have deep striations or layers with crevices in between the layers. I have searched the internet for several hours and have not been able to find anything similar (maybe because I do not know what to search for. lol) Any help you can provide is greatly appreciated! This is a very interesting rock and i would love to know its story! Thank you, Alisha Quote Link to post Share on other sites
Morlock 1,730 Posted December 31, 2020 Share Posted December 31, 2020 I'm not sure exactly what you have. My first thought was crinoids but I don't think it's that.. My next thought was stromatolites but not sure on that either. I'm sure there's a fossil forum that might be able to answer your question.. If you find out, let us know as I'm curious myself. Quote Link to post Share on other sites
Stillweaver hillbelli 325 Posted December 31, 2020 Share Posted December 31, 2020 I first thought I was seeing crab critters(horseshoe) then I saw something like poppy flower all swollenup. ANY museums nearby, universities? Quote Link to post Share on other sites
4meter 201 Posted December 31, 2020 Share Posted December 31, 2020 Hello Dilla1080, I believe you have a sedimentary rock with "molds" created by "load casts" features. From the photo # 4 it is clearly shown that there are alternating layers; some look like sandstone others shale. When the sediments were deposited as sand (sandstone) & mud (shale) a denser, thicker sand layer, which was rapidly deposited over the muds, sank into, and displaced the muds. This created the pattern seen in photo #1 & #2. Later the whole sequence was "cemented" together into a solid rock layer. Erosion has exposed the rock and we now see the "molds" or "holes" in the lower layers in which the sand sank into. The sand has been removed by erosion or broke away from this layer when the rock weathered out of the rock layer. Its a very nice rock you have there. 1 1 Quote Link to post Share on other sites
Stillweaver hillbelli 325 Posted December 31, 2020 Share Posted December 31, 2020 9 minutes ago, 4meter said: Hello Dilla1080, I believe you have a sedimentary rock with "molds" created by "load casts" features. From the photo # 4 it is clearly shown that there are alternating layers; some look like sandstone others shale. When the sediments were deposited as sand (sandstone) & mud (shale) a denser, thicker sand layer, which was rapidly deposited over the muds, sank into, and displaced the muds. ......... INDIANA Jones said^^ Quote Link to post Share on other sites
Dilla1080 1 Posted December 31, 2020 Author Share Posted December 31, 2020 wow thank you for all the replies! it is definitely very interesting looking! It doesn't look like any of the other rocks I have or seen in my grandfather's collection. and the weight of it is shockingly heavy! I have become obsessed with figuring this out and these 2 pics are the closest I found on the internet that looks like it, at least as far as the "design". But then again, I don't have a trained eye for these things! I have also attached a few other pics that i couldnt post originally because i maxed out on pic size. I will google these other things yall have mentioned and see what i can learn! I really want to know its story! Quote Link to post Share on other sites
Bedrock Bob 4,061 Posted December 31, 2020 Share Posted December 31, 2020 It looks like hematite to me. It is an iron replacement of something. Quote Link to post Share on other sites
Dilla1080 1 Posted December 31, 2020 Author Share Posted December 31, 2020 hi Bedrock Bob, when you say replacement, what does that mean? thanks! Quote Link to post Share on other sites
4meter 201 Posted December 31, 2020 Share Posted December 31, 2020 Research the "laminated brown ores (iron) of Texas. The specimen does look like an example of sedimentary iron ore formations. Quote Link to post Share on other sites
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