confused2 Posted May 7, 2012 Share Posted May 7, 2012 I found these rocks on a flat outcropping in southwest Utah. The outcropping had a slight angle and was surrounded by sand. There were hundreds of them in a small area, maybe 20 yards wide and a bit longer--the rocks had obviously rolled down the slight incline. Rocks A and C are round. Rock E is darker and shaped like a clamshell. Rocks C and D were found as shown, split open very evenly through the middle. Both hallow. They are all quite hard. Rock E is harder than A and smoother that the "sandy" feeling rock A. My stainless steel knife can hardly make a scratch in rock A. I tried slamming rock A down on some hard outcropping nearby. It just bounced. When I got home, I put another one just like A in a vice and cracked it open. It too cracked open pretty much in the middle. Image B shows the result. The inside is softer that the outer shell. I can scrape some of the lighter colored interior out, but it is still quite hard. Can anyone tell me what these rocks are? Link to comment Share on other sites More sharing options...
jpc Posted May 7, 2012 Share Posted May 7, 2012 These seem to be what we concretions. Concretions are basically hard, roundish rocks that form within softer rock. In some places they have fossils in them, in other places, none. Also in some places they are extremely common and will do exactly as you described... weather out of a hill and roll down to the base. Often concretions have different layering as some of yours show. Link to comment Share on other sites More sharing options...
confused2 Posted May 7, 2012 Author Share Posted May 7, 2012 Thanks. Sounds somewhat familiar from my geology classes from about 30 years ago! Link to comment Share on other sites More sharing options...
AgrilusHunter Posted May 7, 2012 Share Posted May 7, 2012 Moqui marbles for sure! Moqui marbles are hematite (iron oxide) concretions and are quite common in parts of Utah. They are also quite common on Mars, though they are much smaller there. NASA calls them 'blue berries', but they are just small hematite concretions. Cool stuff. Its been years since I've gotten to collect some of these. There are places in Utah were they literally cover the ground. "They ... savoured the strange warm glow of being much more ignorant than ordinary people, who were only ignorant of ordinary things." -- Terry Pratchett Link to comment Share on other sites More sharing options...
confused2 Posted May 7, 2012 Author Share Posted May 7, 2012 I think you are right. At least a search of internet shows Moqui marbles that look just like the ones I have sitting here and ALMOST as nice as the ones I found. Thanks for the reply. Link to comment Share on other sites More sharing options...
AgrilusHunter Posted May 7, 2012 Share Posted May 7, 2012 ... and ALMOST as nice as the ones I found ... "They ... savoured the strange warm glow of being much more ignorant than ordinary people, who were only ignorant of ordinary things." -- Terry Pratchett Link to comment Share on other sites More sharing options...
Shawn71 Posted May 8, 2012 Share Posted May 8, 2012 septarian nodules are common in Utah but they aren't hollow. www.EarthFragments.com Link to comment Share on other sites More sharing options...
confused2 Posted May 8, 2012 Author Share Posted May 8, 2012 The ones I found were not hollow. They had at some point over time been split open and the softer inside weathered away. Link to comment Share on other sites More sharing options...
painshill Posted May 8, 2012 Share Posted May 8, 2012 (edited) Yes... absolutely Moqui marbles for sure. Theyre concretions of iron oxides in sandstone and are particularly common in the Navajo Sandstone Formations of Utah and across to the Colorado Plateau. Anything up to 190 million years old. The matrix is sandstone, cemented by hematite (Fe2O3), and goethite (FeOOH). They come in all kinds of odd shapes mostly spheres or fat discus shapes. Some have concentric rings and grooves around them, some have angular crystals sticking out of them and some have sharp points sticking out that look like a star has been embedded in them. The smooth round ones are also known as Navajo cherries. Those generally have a sandstone interior and an iron oxide exterior in two distinct layers. If they split open, the sandstone may weather out and leave a hollow. Heres a few odd-shaped ones from my collection: Edited May 8, 2012 by painshill Roger I keep six honest serving-men (they taught me all I knew);Their names are What and Why and When and How and Where and Who [Rudyard Kipling] Link to comment Share on other sites More sharing options...
AgrilusHunter Posted May 8, 2012 Share Posted May 8, 2012 Nice! Love that third example. "They ... savoured the strange warm glow of being much more ignorant than ordinary people, who were only ignorant of ordinary things." -- Terry Pratchett Link to comment Share on other sites More sharing options...
AzMin Posted May 11, 2012 Share Posted May 11, 2012 Hey Painshill, The crystals on the outside of your third specimen are cubic. That would suggest that they are, or were, Magnetite. Magnetite can alter over time to become Hematite or Goethite. If a magnet sticks, it is still Magnetite. If not, it would be considered a pseudomorph; Hematite (or maybe Goethite) after Magnetite. But, you probably already knew that. Nice pieces! Link to comment Share on other sites More sharing options...
Bill Posted May 11, 2012 Share Posted May 11, 2012 I would suggest the cubic xtls were/are Pyrite. Possibly now Goethite psuedomorphs. KOF, Bill. Welcome to the forum, all new members www.ukfossils check it out. Link to comment Share on other sites More sharing options...
painshill Posted June 2, 2012 Share Posted June 2, 2012 Yeah, all of the above is possible. These things are frequently pyritized to some degree and may well have had elements of magnetite at some time. Those are no longer magnetitic and that’s typically the case for Moquis. There is a very similar form found in Kansas, but with different composition and properties. They are known as Kansas “Pop Rocks”, after their habit of exploding if dropped into a fire. Here’s a couple: They have another name, which I refuse to give here since I have a personal objection to it. That name has been trademarked by someone who sells “special versions” of these rocks. They are collected on the trademark owner’s property from the base of a geological “pyramid” feature and sold as “female” and “male” - ying and yang - (the knobbly one is apparently the male and the rarer of the two). The target market seems to be “new-agers”, on the basis that the stones have “spiritual energy”. The vendor “activates” the stones before they are shipped out and you get a certificate of authenticity. You couldn’t print what I think of all that! They are however odd, because they are often naturally magnetised (as opposed to magnetic)… ie they may behave like a magnet and attract ferrous items, albeit weakly. Also, if you hold them loosely and slowly bring them together with slight rotation, you can feel random forces of attraction and repulsion. They “kick” slightly in your hands, which is kind of weird. I’m sure this is because they contain thousands of tiny crystals of magnetite in cavities within the concretion. Give them a shake and you get a different effect. It depends on how the north and south poles of those tiny individual crystals are oriented. The prices are exorbitant (my opinion)… a nice matched pair like mine wouldn’t get you much change out of 200 dollars! Oh, and the stones “vibrate” to the numbers 1 and 9. Apparently. It is also claimed that these stones need to be “handled” frequently to protect their metaphysical properties. That’s partly true, since they have a habit of disintegrating suddenly by further oxidation. I suspect that handling them transfers an oily film to the surface that helps keep out oxygen. Roger I keep six honest serving-men (they taught me all I knew);Their names are What and Why and When and How and Where and Who [Rudyard Kipling] Link to comment Share on other sites More sharing options...
Finder Posted March 26, 2013 Share Posted March 26, 2013 They look like gastroliths. Considering where found and by the number of them you said I would feel certain its a prehistoric animal gastrolith. Link to comment Share on other sites More sharing options...
painshill Posted March 26, 2013 Share Posted March 26, 2013 (edited) They look like gastroliths. Considering where found and by the number of them you said I would feel certain its a prehistoric animal gastrolith. Negative. Some of them have "shells". They're concretionary. Utah is famed for them. Edited March 26, 2013 by painshill Roger I keep six honest serving-men (they taught me all I knew);Their names are What and Why and When and How and Where and Who [Rudyard Kipling] Link to comment Share on other sites More sharing options...
Bullsnake Posted March 26, 2013 Share Posted March 26, 2013 ...They have another name, which I refuse to give here... Out of curiosity, I did a slight search. I see what you mean, Painshill! A seller was touting them as authenticated to be 450-500 million years old from Western Kansas! Caveat emptor, for sure! Steve Link to comment Share on other sites More sharing options...
painshill Posted March 26, 2013 Share Posted March 26, 2013 (edited) Yes... if anyone is prepared to pay those kinds of prices then drop me a mail! I'll activate them, bless them, consecrate them, certify them, provide a dog license with the word "dog" crossed out and the word "paranormal" written in red crayon. Whatever you want. These things have been found on Mars too. The Mars rover Opportunity discovered millions of similar small spherules composed of hematite during its exploration missions at Meridiani Planum. They were dubbed Martian “Blueberries” since they appeared blue in the initially uncorrected false-colour images. They are embedded in evaporate sulphate salt deposits and also lying loose on the surface. Further evidence that there was once a lot of water on Mars. Here’s a couple of pics [from NASA/JPL-Caltech/Cornell University] Mostly the Martian ones are only a few milimetres - the size of peppercorns downwards - and I think that's the size for those images. In September, the rover found another swathe of them near its landing site which were rather bigger - about the size of children's marbles. Edited March 26, 2013 by painshill Roger I keep six honest serving-men (they taught me all I knew);Their names are What and Why and When and How and Where and Who [Rudyard Kipling] Link to comment Share on other sites More sharing options...
Missourian Posted March 26, 2013 Share Posted March 26, 2013 A seller was touting them as authenticated to be 450-500 million years old from Western Kansas! "Um, well.... that's not entirely untrue. Yes, they came from the Cretaceous, but.... the atoms making up the <redacted>s were around 450-500 million years ago...." Context is critical. Link to comment Share on other sites More sharing options...
Bullsnake Posted March 26, 2013 Share Posted March 26, 2013 "Um, well.... that's not entirely untrue. Yes, they came from the Cretaceous, but.... the atoms making up the <redacted>s were around 450-500 million years ago...." I stand corrected. Steve Link to comment Share on other sites More sharing options...
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