from various sources on the web (google the quotes to find them)
Quote:The crystals are generally salts and/or calcium oxalate crystals (kidney stone incarnates). People have bioassayed them before. Whatever they are, they're not active.
Quote:Hey, just cooked up some Pedro tea, and there's these strange crystalline things at the bottom, when it settles...
That's when I noticed the "crystals" looks alot like silica, i looked at them under 40x magnification, and quite rounded shape too them...
Tasted a little bit, Slight bitterness, and easy too crush with teeth..
Quote:http://www.ncbi.nlm.nih..../pmc/articles/PMC148931/The chemical composition and morphology of solid material isolated from various Cactaceae species have been analyzed. All of the tested specimens deposited high-purity calcium oxalate crystals in their succulent modified stems. These deposits occurred most frequently as round-shaped druses
Note that in that study every single specimen they checked had these types of crystals.
I have yet to see a plant without them, but they are larger and more prominent in some specimens, especially older ones. The plants accumulate calcium with age and something like 80% of their dry weight can be composed of these crystals in some cases! 2-5% is more common though.
If you look close at a slice of the plants these crystals should be visible to the naked eye.
People have ingested them without harm many many times. Peyote contains them for example, so do Nopales, which are cactus food items. They seem fairly harmless.