'green mountains' is a correct and usable part of a sentence in written English.
For example, you could write: "The view of the rolling, green mountains was truly spectacular."
Hundreds of thousands of shanties scar the surrounding green mountains.
The green mountains of the Congo loomed in the distance.
Green mountains and a pristine lake shimmer on the horizon.
We motored unhurriedly through an idyllic tricolored world — brown river, green mountains, blue sky.
Nagaland is known for its green mountains and the folk traditions of the Naga people.
Cetinje is in a valley between green mountains and the Adriatic Sea.
Small blue-green mountains, mangrove swamps, land mines and shark-inhabited waters lie beyond.
Our Green Mountains will remain green in the future only with the right decisions now.
There is green in Vermont's Green Mountains -- but not the kind that environmentalists and tourists flock to see.
The westernmost ranges the Taconics, Berkshires, and Green Mountains show a strong north south lineation like the Ridge and Valley.
Vermont is the greenest state, and not just because of the Green Mountains and Ben & Jerry's.
