Posted 2 days ago

Any geologists here? I found a rock today

Hey all, I found this rock under a hedge today while mowing the grass.
It's really smooth and shiny like it came from a riverbed.
Is it unusual or am I just ignorant?
Thanks 4329501_1.jpg
Community Updates
New Comment

38 Comments

sorted by
's avatar
  1. Wongy111's avatar
    psychobitchfromhell's avatar
    Looks like a river worn flint pebble to me, but I'm an archaeologist, not a geologist so I could easily be wrong.
  2. Ringfinger's avatar
    Where do you live? From what I remember from school (ok, we used quills and parchment back in the old days) a lot of rocks were smoothed out and tumbled in the ice age by glaciers moving south down Britain. They petered out and were deposited (when the glaciers started melting) along the south Midlands and across east anglia. Could be one of them?
    psychobitchfromhell's avatar
    That's what's known as a glacial erratic. You can find big boulders of non local stones which were dumped miles from where they originated when the glaciers melted, and smaller, rounded rocks that were rolled along the bottom of the glacier as it progressed.
  3. Shue's avatar
    I asked my geologist friend, nerdy rock lady, and she said;

    "That is is a surprisingly shiny rock and for that level of shininess I'd expect it to either be hand-polished or a gastrolith

    as someone said in the comments, it could be a piece of flint/chert that was polished naturally through water/glacial action, since those tend to have a waxy look

    a gastrolith is a stone that certain animals swallow to help with digestion and they tend to have a waxy-looking surface due to being etched by stomach acids"

    oh and apparently the voids on the surface suggest fossils (edited)
    psychobitchfromhell's avatar
    So, the archaeologist at the geologist agree. It is probably flint. Don't agree with the gastrolith business purely due to the size, unless it was a dinosaur
  4. EndlessWaves's avatar
    Flint is hard and brittle. With that much scoring and rounding on the black surface I'd guess it's not flint.

    It certainly looks like something that formed in a nodule in a similar way though.
    psychobitchfromhell's avatar
    The outside of flint will look like that if it has been in a river bed, believe me. Go to Norfolk and look at all the flint pebble walls and cottages there
  5. Kornelius's avatar
    cute pet, whats his name?
    JoShmo's avatar
    Author
    Balboa
  6. TristanDeCoonha's avatar
    Don't ask Sheldon
    cornishscouse's avatar
    Geeeooo
  8. umirza85's avatar
    52598592-XEnbH.jpg
  10. Wongy111's avatar
    New garden rock !
    I know what it is, but do you ?
    52609708-28TFN.jpg
    qbs's avatar
    Not the best photo, but could be a bit of weathered broken concrete.
's avatar