Any idea if these markings are nature or manmade?

[jmchandler]

I would appreciate any of your input. Like the rocks in my other posts, this was found in my backyard before any landscaping was done. I'm such a newbie, but I think it is flint, or chert. I would like to know if the marks are man made or just natural. Thank you! Bridgeport, Tx

 

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[Buckleberry]

Nothing I can see is indicative of it being altered by man.

 

[tomclark]

I agree natural. No purposeful pecking, grinding, chipping, flaking or bashing

 

[jmchandler]

Ok. Thank you

 

[antmike915]

All the above