Mystery Beads.... and Copper

I love the look of these beads with the copper and leather. My family brought them back from Mexico last year for me, but unfortunately, we've misplaced the name of the beads! They almost seem as though they are a clay of some type because the drill hole seems like a chalk or hardened clay, but... we were told they are stones of some kind. If you have any idea what these might be, I'd really appreciate the information. I've been searching for a while, but haven't found anything even close.

I hammered these copper pieces and then used a mixed color of copper to accent the metal. The necklace is meant to be worn close to the neck like a choker. I think, having chatted with some of you now on this, I might call them Artistic Beads if I can't identify them as a natural stone. They are just beautiful and I hope the images do them some justice.

Again - any further help with the beads would be great, if you recognize them!
Many hugs.

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