Ok, I got something wild for you today...
Someone sent me a sample of a frankincense they wanted my opinion on.
It's low quality, small grain resin with some occasional bits of dirt mixed in, labelled "Carterii Ethiopia".

Looks normal right?
Yesterday, I lit a tiny charcoal and started to placing single kernels of that frankincense on it.
What I would expect to see from a frankincense, is that it will start to bubble, smoke, change its colour, char, shrink and finally turn to embers and stop smoking.
What I saw with most of the kernels was almost no bubbling; smoke, then sort of a puffing with the kernel turning brownish-black - it stops smoking at that point and will no longer burn. At all.
When I let it cool off, I crushed the charred remains between my fingers and found WHITE quartz-like bits in the inside!
Here's a picture:

When I get frankincense, I will usually always taste it. Not all Frankincense varieties are suited for chewing, but I'm still curious how they tease.
Putting this frankincense in your mouth will barely taste of anything but feel like sand. It doesn't soften, it doesn't fall apart. I didn't dare to bite on it.
After finding this, I also put a spoonful in water and washed it.
Some single bits turned white, which is what I would expect. Most of it just sunk and pretty much didn't change. But I didn't leave it in for long. I should do another try and let it soak for several hours...
Here's a before and after picture:

The washed kernels on the right are not fully dry yet.
After that, I started to hold them in a flame.
Some would actually melt and fall into the candle I was using, but a lot would burn shortly and have the white crystal inside - either a big one or like sand that was formally glued together by the resin.
I made a video:
https://youtube.com/shorts/WZBb07Fxr10?si=uN-YFY3bXmx6GYUI
Has anyone of you ever run into anything remotely similar?
Might this be straight up frankincenses, adulterated with some kind of small gravel to make it heavier?
It's not uncommon to find some bits and an occasional stone in a batch of frankincense, but this is like the stone bits are covered with frankincense.
Is there any way this can occur naturally?
If this is not stone, what is it?
A little update with some context:
I had sent an email with what I found to whom I got that sample from and just got his reply.
He bought a significant amount of that stuff because it was from a formally trusted source. 🙁 That SUCKS!
He tells me, it has lately become harder to source frankincense directly from Africa (he's in India).