Muffinsaurus Posted August 16, 2022 Share Posted August 16, 2022 I found this bizarre (to me at least) rock in a creek in Floyd County, Kentucky. The dark area of the rock is very resistant to scratching with metal tools. The lighter part feels and acts like an extra hard sandstone. Recent flooding may have pushed it down stream. No factories. I find it interesting how it looks like an old melted clump or rotten fruit turned to stone. Just curious as to what kind of rock this might be so that I can research how it is formed. Thanks in advance! Link to comment Share on other sites More sharing options...
Megalodoodle Posted August 16, 2022 Share Posted August 16, 2022 (edited) Could you please perform a streak test for the black bits? If the stone is harder than the streak plate then the plate will be scratched and not the mineral. Also a more exact hardness test would be useful. Edited August 16, 2022 by Megalodoodle 1 Link to comment Share on other sites More sharing options...
Megalodoodle Posted August 16, 2022 Share Posted August 16, 2022 Possibly stream-polished botryoidal goethite? 1 Link to comment Share on other sites More sharing options...
Muffinsaurus Posted August 16, 2022 Author Share Posted August 16, 2022 9 minutes ago, Megalodoodle said: Could you please perform a streak test for the black bits? If the stone is harder than the streak plate then the plate will be scratched and not the mineral. Also a more exact hardness test would be useful. Sorry I don't think I can as I don't have any porcelain, let alone any of the unglazed verity. Is there another way to perform a streak test? Also Sorry for my lack of information. 8 minutes ago, Megalodoodle said: Possibly stream-polished botryoidal goethite? I'll look into this, thank you Link to comment Share on other sites More sharing options...
Megalodoodle Posted August 16, 2022 Share Posted August 16, 2022 Unfortunately there is (at least to my knowledge) no other way of doing a streak test. So your average iron/steel tool, such as a knife, is rated 4-4.5 on the Mohs Hardness Scale. I’d try and see if you can scratch it with a piece of calcite for your scratch test, seeing as how you can scratch it with a knife. 1 Link to comment Share on other sites More sharing options...
Muffinsaurus Posted August 16, 2022 Author Share Posted August 16, 2022 38 minutes ago, Megalodoodle said: Unfortunately there is (at least to my knowledge) no other way of doing a streak test. So your average iron/steel tool, such as a knife, is rated 4-4.5 on the Mohs Hardness Scale. I’d try and see if you can scratch it with a piece of calcite for your scratch test, seeing as how you can scratch it with a knife. Okay, I think I have some around here somewhere. I'll have to locate it. Thank you for your help. Link to comment Share on other sites More sharing options...
Megalodoodle Posted August 16, 2022 Share Posted August 16, 2022 4 minutes ago, Muffinsaurus said: Okay, I think I have some around here somewhere. I'll have to locate it. Thank you for your help. No problem! I enjoy encouraging others’ interest in geology! Link to comment Share on other sites More sharing options...
Fossildude19 Posted August 16, 2022 Share Posted August 16, 2022 The underside of your toilet tank lid is unglazed porcelain. 1 Tim - VETERAN SHALE SPLITTER VFOTM --- APRIL - 2015 __________________________________________________ "In every walk with nature one receives far more than he seeks." John Muir ~ ~ ~ ~ ><))))( *> About Me Link to comment Share on other sites More sharing options...
Muffinsaurus Posted August 17, 2022 Author Share Posted August 17, 2022 15 hours ago, Fossildude19 said: The underside of your toilet tank lid is unglazed porcelain. I have no idea why I didn't even remotely think of that. Thanks! Link to comment Share on other sites More sharing options...
Muffinsaurus Posted August 17, 2022 Author Share Posted August 17, 2022 Okay I got to do the test. The dark part leaves a light brown waxy looking mark that I could rub away with relative ease. The lighter part doesn't leave a mark... Well, it kinda dug into the porcelain, but left no color behind. I'm very unsure what I'm looking for, so I hope I provided the correct information for this test. Link to comment Share on other sites More sharing options...
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