DIY Cosmetics: How to Make Easy Matte Eyeshadows

I recently encountered a product that seemed to have an incomplete ingredients list since the ingredients listed was just: Mica, Iron Oxides

The thing is, the formula was great. It was blendable and works well on bare skin! I decided to test out if it is possible to create a great formula with just iron oxides grounded with sericite mica. Unfortunately, the only sericite mica I have access to are carnauba wax treated sericite mica, and methicone treated sericite mica, so the results I got may be different than if I used just plain sericite mica (and the ingredient list would be: Mica, Iron oxides, Carnauba Wax/Polymethylhydrogen Siloxane instead of just Mica, Iron Oxides).

This was the first experiment I did:

As you can see, my iron oxide & carnauba wax treated sericite mica mix isn't as smooth as the Medium Brown eyeshadow I was swatching, even with a primer.

So I decided I may need to get the precise ratio, so I mixed Ferric Ferrocyanide (I wanted a blue eyeshadow) with carnauba wax treated sericite mica in different quantities and here's the results:

SM = Carnauba Wax Treated Sericite Mica
FF = Ferric Ferrocyanide

As you can see, the perfect mix is somewhere between 4-5 parts carnauba wax treated sericite mica to 1 part Ferric Ferrocyanide. Unfortunately, it now has a bit of a sheen and the colour became much lighter. It also didn't blend as well as shadow I was testing out:

I was wondering if Ferric Ferrocyanide just didn't blend into the mica as well as iron oxides, so I did a 4:1 methicone treated sericite mica & iron oxide mix. Yup, I know this isn't a perfect experiment and I should've stuck to carnauba wax treated sericite mica, but I didn't know what sericite mica to use so I just bought small amounts of the different sericite mica available. Here's the result over bare skin:

Looks perfect! Looks like you can make iron oxide based mattes by just grinding it with methicone/carnauba wax treated sericite mica. But what about when you add micas in? Well, I added Hilite Blue Mica and that's when patchiness set in:

So in conclusion, you can totally make smooth, buttery matte shades by just grinding iron oxides & treated sericite mica, but you have some limitations on what colours you can create.