Trail Mix Physics

I purchased a wide mouth container, roughly the shape of a 5"cube filled with 36 oz. of trail mix composed of roughly equal volumes of:

Peanuts
M&M's
Raisins
Chocolate chips
Peanut butter chips

As I periodically "stir" the contents by pouring a handful out at a time, I notice that, as expected, the slick shelled M&M's tend toward the bottom of the container. However, I am surprised to find lots of peanut skins remaining amongst the M&M's and broken peanut pieces as the container gradually empties. The peanut skins are feather light. Why didn't they work their way to the top of the container as the heavier contents settled?

Quote: Ayecarumba

I purchased a wide mouth container, roughly the shape of a 5"cube filled with 36 oz. of trail mix composed of roughly equal volumes of:

Peanuts
M&M's
Raisins
Chocolate chips
Peanut butter chips

As I periodically "stir" the contents by pouring a handful out at a time, I notice that, as expected, the slick shelled M&M's tend toward the bottom of the container. However, I am surprised to find lots of peanut skins remaining amongst the M&M's and broken peanut pieces as the container gradually empties. The peanut skins are feather light. Why didn't they work their way to the top of the container as the heavier contents settled?

I saw a cool article on a related topic. Will try to find link. In short, it’s not predominantly about weight, it’s about shape. Smaller things tend towards the bottom as they can “fall” through the cracks of bigger things. Doesn’t really explain the M&Ms as I assume they are on the bigger side of what makes up the mix. But maybe it is slick shells as you say.

Edit: here is article: https://medium.com/the-physics-arxiv-blog/brazil-nut-effect-explains-mystery-of-the-boulder-strewn-surface-of-asteroids-e5fae1b6c242

It's the size that counts. (heh heh)

That's why the tiny crumbs and featherweight chip dust is always at the bottom of the bag.

You are touching upon one of the greatest inventions in history: the corning of gunpowder. Particles of different size and shape resulted from keeping gunpowder dry. Once it was weted it could be worked to uniform size and would remain so during shipping.

Quote: unJon

I saw a cool article on a related topic. Will try to find link. In short, it’s not predominantly about weight, it’s about shape. Smaller things tend towards the bottom as they can “fall” through the cracks of bigger things. Doesn’t really explain the M&Ms as I assume they are on the bigger side of what makes up the mix. But maybe it is slick shells as you say.

Edit: here is article: https://medium.com/the-physics-arxiv-blog/brazil-nut-effect-explains-mystery-of-the-boulder-strewn-surface-of-asteroids-e5fae1b6c242

Wow! The example is almost exactly what I experienced. Thanks unJon.