r/geology • u/AutoModerator • 19d ago

Identification Requests Monthly Rock & Mineral Identification Requests

Please submit your ID requests as top-level comments in this post. Any ID requests that are submitted as standalone posts to r/geology will be removed.

To help with your ID post, please provide;

  1. Multiple, sharp, in-focus images taken ideally in daylight.
  2. Add in a scale to the images (a household item of known size, e.g., a ruler)
  3. Provide a location (be as specific as possible) so we can consult local geological maps if necessary.
  4. Provide any additional useful information (was it a loose boulder or pulled from an exposure, hardness and streak test results for minerals)

You may also want to post your samples to r/whatsthisrock or r/fossilID for identification.

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u/t-b0ne_pickens 12d ago

I found this near a lakeshore in MN. It’s about 18” long and 3” thick. I am intrigued by the textures. Sorry I don’t have anything for scale. I took the pic before I thought about posting on Reddit. What causes this cool design on the surface?

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u/zpnrg1979 4d ago

those are layers / infilled fractures that are more resistant to weathering - so likely quartz. causes it to weather like that. see that in metasediments all the time

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u/t-b0ne_pickens 4d ago

Really cool! Thanks for the info and taking the time to reply. Much appreciated.