It's cheap and plentiful. If people make beads from animal feces, why not cement?

I think I can get some cement and try making & breaking a piece to see what it looks like.

You may not be able to replicate... The mix ratios, the type of aggregate, the pH of the water, the cure temperature and TIME can affect the outcome.

I'm reluctant to fracture one of them to compare. In fact I only have one, and it's not a very large one, so maybe it will make the ultimate sacrifice. I'll wait for more input before I destroy it.

If anyone has a powder glass bead with a gray core that is already broken or badly damaged, and you’re willing to donate it to bead research, please let me know, or just post a good macro photo of the fracture surface.

Hi Rosanne,
hereby an example of a grey core (if seen at a distance) powder glass krobo bead. You can see on this bead that the grey is build up from a lot of different colors.
And another possibility, a low fired, ceramic spindle whorl from Mali.
Can you describe the sound while breaking the bead? Was it a dull sound or clear? (Don't know the right description of sounds)
Both pictures from the "boulevard of broken beads" flickr photo stream

I like the clay idea. Your beads look like clay and paint or maybe even a thin coat of powdered glass fired onto clay :)
They are really cool looking beads. Good eye

I cannot break the beads by hand - I hit one with a large hammer with the bead on a concrete floor. So, I can't really say what the sound was like.

If you want to break a bead in a more-controlled manner, just place it vertically on a hard surface, and insert an awl or pointed tool into the perforation, that penetrates, but not all the way into it; and strike the tool with a hammer (once). Depending upon the material, the bead will split in two, divide in some way, or even crumble. JDA.

P.S.—the name "cement" is used for two entirely different products. One is the very hard concrete used in construction, that has many different formulas and uses (and therefore hardnesses and destructibilities). The other is usually resin-based and used as a glue.

Beads have been made from concrete materials, AND from substances (i.e. crushed glass) bound together with glue. And any of these might be characterized as "cement beads."

Maybe this could help.

https://www.go-dove.com/en/auction/view?id=13629854

But my priority would be a nice FTIR spectrometer so I could ID plastics.

And I think atomic absorption spectroscopy would be best to identify the elements in an n inorganic material like concrete.

I'll take one of each!

I am taking a slightly different tack and sent an inquiry to a German cement company that was active since the late 1800s, to ask if they shipped to West Africa. Also if they would do the analysis on a bead and compare to their historical data base. Probably thought I was a loony-tune. So far, no reply.

It seems most if not all my emails to Germany, Belgium, France go into a spam or trash folder or are blocked for some reason. I've asked some German and Belgian colleagues to send the exact same message to the same people in the past, and they get an answer almost immediately. So if I don't hear back I'll probably try the same trick.

The hole "path" looks like what happens when you make the hole early on, then roll the bead more. You can see that the hole near the end of the bead is more flattened than the interior.

I thought they looked like some low-fired locally source clay. Or a poorly-made cement, as Jamie mentioned.

In any case, not glass- or coral-based?

What about contacting industry associations and organizations, such as the below, to see if they have suggestions:

http://www.societyofconcretepetrographers.org/

https://www.concrete.org/ re. ACI, I'd ask to speak to a technical rep.

Perhaps the beads are made of natural cement or clay (that has cementitious properties)? Both would produce materials that, because of impurities, would be much weaker than plant-produced concrete.

I hope you'll let us know what they recommend and what you discover.

Rosanna Robert Liu wrote about these beads in an early Ornament (or maybe in a late Bead Journal). He called them "painted clay" and said they were thought to come from Morocco. If I remember correctly, the article was actually about powder glass and in particular the powder glass which imitates coral(sometimes known as "African Coral"). This was a number of years ago, but at that time he stated that he thought they were relatively rare. I found my first ones at the funky little place in San Diego known as Folk Art International. I think you visited it once. They are, as you have already seen, fragile and the red paint doesn't adhere very well. I have not seen them more than a couple of times in all my looking.

That jibes with Rosanna's initial thoughts about the beads being cementitous. Clay has pozzolanic properties which allows it to cure when mixed with water into a strong cementitous product: https://www.google.com/search?sourceid=navclient&aq=&oq=clay+pozzolana&ie=UTF-8&rlz=1T4ADFA_enUS460US460&q=clay+pozzolana&gs_l=hp...0i22i30l2.0.0.1.213005...........0.mJKXNLzp9QM

I am not following your train of thought.

Rosanna initially said she thought the bead(s) might be "some sort of soft stone or maybe grey coral." (Not cement.)

You suggest, "Clay has pozzolanic properties which allows it to cure when mixed with water into a strong cementitous product." However, the Wiki article says for pozzolana, "The major component is volcanic glass typically present in quantities over 50 wt%." So not a ceramic. And further says, "Zeolite, opal CT and clay minerals are often present in minor quantities as alteration products of the volcanic glass."

I have seen these beads. (Probably from Robert Liu's collection, a very long time ago.). But I have not paid much attention to them. My impression was that they were poorly-fired (still soft and friable) clay. They would not have the hardness and integrity of typical powderglass. However, I could not rule-out the possibility that they might be a crudely-made cement. I will ask Robert, the next time I speak with him, whether he has an opinion. JDA.

I heard back from the cement expert, and his tests showed that the material is Portland cement. The paint has lead in it.