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enter image description hereenter image description hereenter image description hereenter image description here

I found this in Topanga Canyon, California (LOS ANGELES). It can be scratched with a penny, but not my fingernail: hardness is about a 2.75 I guess. The size of a baseball.

I found this on the edge of a field on a mountain ranch within the Santa Monica Mountains. We are 5 miles north of the Pacific Ocean.

Thank you JulPal! I’ve been looking at concretion pics for months... just never saw anything similar. Yes, this item is round, but I’m puzzled by the white fibrous outer ‘shell’ as well as the embryonic interior and crystallized center.

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closed as off-topic by Jan Doggen, arkaia, trond hansen, Fred, uhoh Aug 31 at 11:17

This question appears to be off-topic. The users who voted to close gave this specific reason:

  • "Questions about rock identification requests are off-topic. For more information, see the announcement on meta." – Jan Doggen, arkaia, trond hansen, Fred, uhoh
If this question can be reworded to fit the rules in the help center, please edit the question.

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    $\begingroup$ Looks like typical concretions... Try googling for 'California concretion' and look at images $\endgroup$ – JulPal Aug 18 '18 at 8:26
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Its a concretion, the "fibers" are just crystallization of the material or crystal fill in minor cracks. The image below is a pyrite concretion with pyrite forming the radiating crystals.

enter image description here

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Another chance to get these 'fibers' are septarian concretions... See here for example

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