Mount Kinabalu is formed from granodiorite. This is an intrusive igneous rock, very similar to granite but with a different proportion of plagioclase and feldspar.
I took the photo below on my ascent to Laban Rata. Ascent, that is, as in climbing the stairs rather than something more skillful.
Laban Rata is pretty much at the altitude where the vegetation peters out and the base granite starts. The trek there is through the jungle/rainforest so it can be pretty warm and humid. Most of the climb that I recall was this seemingly endless zigzag of stairs cut into the side of the hill and shored up with wood or stone, without which the entire climb would be a muddy scramble.
This is a view of Mount Kinabalu taken from the Park HQ in the evening. The sun has already set on the Park HQ but still illuminates the mountain top.