Mineral question?

[Missespenaloza]

Hello! I’m trying to nourish my goats properly (which seems harder than it should be!) and there is a recipe by pat coleby for a mineral mix that contains something called “fine yellow (99%).” Can anyone tell me what this is? I’ve googled and I can’t find anything relevant. Thank you!

 

[animalmom]

I think it is animal salt with some additive.

 

[frustratedearthmother]

My guess is that it's powdered sulfur.