I don't see any hard to see icons, please, be specific about which are.
I said hard to read.
Look at fire+ice. i suppose its steam, but on its own it could be snow, a rock, a molten marshmallow, a soggy fallen over plushy.
Similar problems are with rock+ice, leaf+fire, wood+fire, water+water, fire+rock, gold+gold, each to varying degrees of readability.
it looks like you're designing things to be able to fit in a hand. i'm not sure if that's a deliberate limitation or if it just happened to turn out that way.
If that's the case you could also create things like fire+rock=volcano. rock+water=waterfall or a well.