Muscadine

I started reading this old historical fiction novel the other night that I've been hauling around for years. I became a fan of the author in my twenties and have read most of his stuff, though my memories of specific plot details are real hazy.

Anyhoo, I was just gonna flip through this 1988 paperback and then toss it on the Get Rid Of pile but, damnit, the author keeps surprising me. He does things with adjectives I don't know how to do. I'm envious.

I came across one phrase the other night that blew me away:
... they fled into the muscadine shadows.

And another: ... the darkness emerald with waking dreams.

There's more: ... the yard swirled with children and ... he took it for its earthing power.

I'm having trouble deciding whether you can commandeer nouns like 'emerald' and force them into adjective work. Is it grammatically correct?

I don't care. I think I'll keep (re-)reading.