# Bone or Rock? **URL:** \ **Category:** Factual Questions\ **Created:** [July 30, 2021, 8:41pm UTC](https://boards.straightdope.com/t/bone-or-rock/947668 "2021-07-30T20:41:15Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![GreysonCarlisle](https://avatars.discourse-cdn.com/v4/letter/g/a87d85/32.png) [@GreysonCarlisle](https://boards.straightdope.com/u/GreysonCarlisle)\ **Post date:** [July 30, 2021, 8:41pm UTC](https://boards.straightdope.com/t/bone-or-rock/947668/1 "2021-07-30T20:41:15Z")
Images here: [Bone or Rock — ImgBB](https://ibb.co/album/VVpp4P) Is this a fossil, a very old bone, or just a funny-looking rock? Just realized that I should have put something in to show scale. The rock is about 1-1/2 inches long. ---
**Author:** ![kayaker](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kayaker/32/441_2.png) [@kayaker](https://boards.straightdope.com/u/kayaker)\ **Post date:** [July 30, 2021, 8:45pm UTC](https://boards.straightdope.com/t/bone-or-rock/947668/2 "2021-07-30T20:45:05Z")
I’ll bet @MrDibble knows. ---
**Author:** ![DCnDC](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dcndc/32/2842_2.png) [@DCnDC](https://boards.straightdope.com/u/DCnDC)\ **Post date:** [July 30, 2021, 8:56pm UTC](https://boards.straightdope.com/t/bone-or-rock/947668/3 "2021-07-30T20:56:49Z")
Not an expert at all, but I’m leaning toward rock. If it were a bone I would WAG that it should be hollow or there should be a distinct difference in color and/or texture where the bone becomes marrow. But admittedly, I’m completely talking out of my ass. Check out the photos on this page: [Would Like Help Identifying Possible Bone Fossils | Dinosaur Home](https://www.dinosaurhome.com/would-like-help-identifying-possible-bone-fossils-36213.html) ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [July 30, 2021, 9:02pm UTC](https://boards.straightdope.com/t/bone-or-rock/947668/4 "2021-07-30T21:02:37Z")
We need a close macro shot of surfaces. To look for haversian canals. Also, thread title sounds like it belongs in Cafe Society. ---
**Author:** ![GreysonCarlisle](https://avatars.discourse-cdn.com/v4/letter/g/a87d85/32.png) [@GreysonCarlisle](https://boards.straightdope.com/u/GreysonCarlisle)\ **Post date:** [July 30, 2021, 9:21pm UTC](https://boards.straightdope.com/t/bone-or-rock/947668/5 "2021-07-30T21:21:14Z")
Got a larger pic of what “looks” like it might be marrow [here](https://ibb.co/tYP2jY7). ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [July 30, 2021, 9:50pm UTC](https://boards.straightdope.com/t/bone-or-rock/947668/6 "2021-07-30T21:50:49Z")
Photo is out of focus, but it hasn’t changed my leaning towards “rock”. (It could tip the other way with better photos, though.) Here is a closeup of a fossil bone fragment I found on a beach. [[Album] imgur.com ![](https://i.imgur.com/kPh6vLA.jpeg?fb "imgur.com") ](https://imgur.com/a/T1h6ycH) ---
**Author:** ![Banksiaman](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/banksiaman/32/3334_2.png) [@Banksiaman](https://boards.straightdope.com/u/Banksiaman)\ **Post date:** [July 30, 2021, 9:53pm UTC](https://boards.straightdope.com/t/bone-or-rock/947668/7 "2021-07-30T21:53:41Z")
I’d go for rock - some chunk of seamed quartz. I can see why you’d be tempted to consider it to be bone though. ---
**Author:** ![GreysonCarlisle](https://avatars.discourse-cdn.com/v4/letter/g/a87d85/32.png) [@GreysonCarlisle](https://boards.straightdope.com/u/GreysonCarlisle)\ **Post date:** [July 30, 2021, 10:08pm UTC](https://boards.straightdope.com/t/bone-or-rock/947668/8 "2021-07-30T22:08:18Z")
Thanks, everybody. I’m just gonna consider it a rock and run it through the polisher. ---
**Author:** ![MrDibble](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mrdibble/32/114_2.png) [@MrDibble](https://boards.straightdope.com/u/MrDibble)\ **Post date:** [July 31, 2021, 11:02am UTC](https://boards.straightdope.com/t/bone-or-rock/947668/9 "2021-07-31T11:02:45Z")
I’d say rock as well. In the one close-up, the finely-textured area is clearly crystalline. And the smooth areas (that you might think were the articulation points of this was e.g the head of a femur) also have a more massive crystalline texture, and also includes the finer-textured parts where no ball joint would have them. Veins aren’t out of the question in fossils, but usually the fossil would be very deformed as well. ---
**Author:** ![elbows](https://avatars.discourse-cdn.com/v4/letter/e/b3f665/32.png) [@elbows](https://boards.straightdope.com/u/elbows)\ **Post date:** [July 31, 2021, 11:16am UTC](https://boards.straightdope.com/t/bone-or-rock/947668/10 "2021-07-31T11:16:52Z")
I have several pieces just like these! And have wondered the same, since collecting them. Where did you collect these? (I picked mine up off a beach on a South Pacific island.) I am wildly interested to know what it looks like coming out of the polisher, please post a photo! ---
**Author:** ![Jackmannii](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jackmannii/32/311_2.png) [@Jackmannii](https://boards.straightdope.com/u/Jackmannii)\ **Post date:** [July 31, 2021, 1:38pm UTC](https://boards.straightdope.com/t/bone-or-rock/947668/11 "2021-07-31T13:38:59Z")
Did the OP dig that up in his basement? 🙄 ---
**Author:** ![GreysonCarlisle](https://avatars.discourse-cdn.com/v4/letter/g/a87d85/32.png) [@GreysonCarlisle](https://boards.straightdope.com/u/GreysonCarlisle)\ **Post date:** [July 31, 2021, 4:01pm UTC](https://boards.straightdope.com/t/bone-or-rock/947668/12 "2021-07-31T16:01:15Z")
> [@MrDibble](#): > > I’d say rock as well. > In the one close-up, the finely-textured area is clearly crystalline. And the smooth areas (that you might think were the articulation points of this was e.g the head of a femur) also have a more massive crystalline texture, and also includes the finer-textured parts where no ball joint would have them. Veins aren’t out of the question in fossils, but usually the fossil would be very deformed as well. Thanks. I was hoping it would be an old bone or maybe an antler. But funny-looking rock seems to be the consensus, and this confirms it. > [@elbows](#): > > I have several pieces just like these! And have wondered the same, since collecting them. > > Where did you collect these? (I picked mine up off a beach on a South Pacific island.) > > I am wildly interested to know what it looks like coming out of the polisher, please post a photo! The guy who originally owned this house was crazy for his rock beds. My girlfriend surprised me one day with a rock polisher, so we’ve been collecting the prettier rocks and polishing them. Dunno where the guy sourced his rocks. Probably a local supplier here in NW Missouri. I’ll definitely post a pic, but it’ll take a few weeks for the polisher to do its thing. I wish I’d thought to collect rocks when I was running all over the world in the military. ---
**Author:** ![Senegoid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/senegoid/32/6606_2.png) [@Senegoid](https://boards.straightdope.com/u/Senegoid)\ **Post date:** [August 1, 2021, 6:24am UTC](https://boards.straightdope.com/t/bone-or-rock/947668/13 "2021-08-01T06:24:10Z")
Possibly petrified bone? I’ve seen petrified trees. The organic material is fully replaced by mineral, so it becomes fully rock, not the original organic whatever-it-was – yet the grain and details of the original material are fully preserved in the mineralized structure. ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [August 1, 2021, 7:14am UTC](https://boards.straightdope.com/t/bone-or-rock/947668/14 "2021-08-01T07:14:32Z")
> [@Senegoid](#): > > yet the grain and details of the original material are fully preserved in the mineralized structure. There is no sign that rock has the grain and details of bone. ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [August 2, 2021, 12:04pm UTC](https://boards.straightdope.com/t/bone-or-rock/947668/15 "2021-08-02T12:04:51Z")
An old book I’ve had since I was a kid – **Let’s Find Fossils on the Beach** – said that one way of telling fossil shells from modern ones (where the shell material hasn’t been replaced by stone) is to hold it over a flame for a few seconds. Modern material will give off an odor “like burning hair.” I’ll bet it will work with bone, as well. Disclaimer: Despite years of trying, I’ve never found a fossil on the beach. ---
**Author:** ![MrDibble](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mrdibble/32/114_2.png) [@MrDibble](https://boards.straightdope.com/u/MrDibble)\ **Post date:** [August 2, 2021, 5:35pm UTC](https://boards.straightdope.com/t/bone-or-rock/947668/16 "2021-08-02T17:35:36Z")
You could also drip dilute HCl on it. If the carbonate shell material has been replaced, usually it’s with silica. Carbonate fizzes under acid, silica doesn’t. In fact, a related technique is how replaced shell fossils are freed from some limestone matrices. This also works on bones, because the phosphates in the bones also don’t dissolve. But you do need confidence in the compositions of everything involved. ---
**Author:** ![GreysonCarlisle](https://avatars.discourse-cdn.com/v4/letter/g/a87d85/32.png) [@GreysonCarlisle](https://boards.straightdope.com/u/GreysonCarlisle)\ **Post date:** [August 11, 2021, 8:17pm UTC](https://boards.straightdope.com/t/bone-or-rock/947668/17 "2021-08-11T20:17:51Z")
> [@elbows](#): > > I am wildly interested to know what it looks like coming out of the polisher, please post a photo! I’m not holding out much hope for the little guy. Halfway through the polishing process, and it’s lost a third of its length already. > **[Bone-Half-Polished-001 hosted at ImgBB](https://ibb.co/qMzB9Zj)** > > Image Bone-Half-Polished-001 in Bone or Rock album ---
**Author:** ![elbows](https://avatars.discourse-cdn.com/v4/letter/e/b3f665/32.png) [@elbows](https://boards.straightdope.com/u/elbows)\ **Post date:** [August 11, 2021, 8:36pm UTC](https://boards.straightdope.com/t/bone-or-rock/947668/18 "2021-08-11T20:36:15Z")
OOoh, still interesting though! Thanks for posting this, I appreciate it very much! ---
**Author:** ![MrDibble](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mrdibble/32/114_2.png) [@MrDibble](https://boards.straightdope.com/u/MrDibble)\ **Post date:** [August 12, 2021, 6:26am UTC](https://boards.straightdope.com/t/bone-or-rock/947668/19 "2021-08-12T06:26:36Z")
I still think it would be interesting to drip some acid on it. If you can get some HCl (pool acid, or cleaning muriatic acid), that’s best, but even acetic acid or lemon juice should work in a pinch. ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [August 12, 2021, 7:02am UTC](https://boards.straightdope.com/t/bone-or-rock/947668/20 "2021-08-12T07:02:27Z")
> [@GreysonCarlisle](#): > > I’m not holding out much hope for the little guy. Halfway through the polishing process, and it’s lost a third of its length already. They have pills for that now. [Next page](https://boards.straightdope.com/t/bone-or-rock/947668.md?page=2)