Don't put dirt in your mouth.

Do you recall past geology field trips when a university geology professor might put dirt in his or her mouth in order to estimate the "grit" percentage of fine-grained sediments?  They might explain how SILT would feel gritty between their teeth and how they could estimate it's presence, and percentage.

Professors who command the highest level of respect and reverence could be seen "biting down" on bits of dust, dirt, and mud....and then declaring the precise particle size of the sample.  That seems like an amazing feat and today in 2020 it calls into question how they "calibrated" their skills.  LOL.

Today, there's good reason not to put dirt in their (our) mouth to estimate particle size:

1. Potential chemicals or contaminants in the soil can harm us.
2. There's no published standard for the "Grit Between the Teeth" analysis.
3. Reproducible test procedures seem unlikely.

HOWEVER.....THERE IS AN EXCEPTION!

Here is some Edible Sand!  There's a decent chance it would get a good "grade".  (that's a particle size analysis pun).

Yum!

There are more exceptions too.  If you Google-Search "edible silt" or "Loess Cookies", you will find some interesting results about a perspective on improving health by eating dirt.  (I still don't recommend putting dirt in your mouth, unless directed by your personal physician).

Despite the rumors, eating FAT CLAY probably doesn't make you skinny.