In my experience with sooooo many different suppliers and soooo many different kava, I have also seen this and it looks to me like it might still be part of the earth that it was grown in. To give you an example there is a kava vendor in Hawaii, not me, that when you look at his kava under a microscope you will see the black rocks, it is the black cinder that they plant the kava in. I know this person and I know how he plants so I know that the black cinder is what is in his kava. Maybe you are seeing something like that, just part of the good ground that it came from.
It is a sign of not being processed or cleaned properly, you can look and look and look and you will not find that in my kava. I do not grow my kava in cinder for just that reason. I hope this helps. Aloha.
Chris
