Black Beads

I really can't tell what are those, natural, man made?
Any idea?
Thanks

 

I'll take a guess, maybe Oaxaca pottery beads?

 

Could be basalt beads.

 

At first I also thought that they could be made of lava rock but would not there be a lot of craters?
The beads appear to be grayish on the inside. Oaxaca pottery gets its black color by polishing with quartz stone before firing. If these beads were polished would not they be with more even surface?

 

Lake Superior basalt beads do not have "craters" like those from some other locations.

 

I can't say anything about Oaxaca beads other than the one shot of the chipped bead looks like blackened pottery to me so I googled Oaxaca and found some beads. This is what one says;

"Each bead is polished before full drying to give its characteristic tone, shiny black patina."

https://mexicanias.pswebstore.com/e...xaca.html?search_query=oaxaca+beads&results=2