You could create the peak you want now if you're not happy. But I think you could manage with that as well. I like the sheer faces if it's going to be rock.
Water based acrylic flat craft paints. Black or dark grey as as a base color. About two bottles worth of 2oz at about a buck each will cover it; or spray the basebcolor if it pleases you, but no gaps; You need a total fill in cracks.
Then dry brush a few shades of grey. Start darker; lighter shades on final highlights. Then snow. Thick for a rouñded flowing look. Thin for icy, maybe a blue tint. Satin or semi-gloss for "wet" snow. Blotchy drybrush for frost. Nothing stopping you from using two shades of white, drybrush a pure white on the highlights.
One grey on black, plain styrofoam, vertical strokes here for implied weathered edge up high(a weather wash would help, this is "raw" for the look)
On cut box cutter sliced up styrofoam
Thick snow, frosted red brick, 2 blacks, 2 greys, gold in the tunnel (looks red-brown, you may see differently, one of those color tricks; live, it's gold metallic highlights.)
More color tricks.
Some of the dark green is added because the green means copper ore. But there is also metallic copper drybrushing here that appears as green. In person it is also copper... and some gold too...again, it looks brown in the photo.
Screen and spackle with "old school" look.
Hmmm shoulda changed it to a black&white shot to illustrate grey tone, but you can break this down to blk, drk gry, lt gry, white. (Brwn,grn, being greys)