A small seam of white asbestos was discovered however insufficient amounts to commercially mine.

Surrounding the crown of the mount is a geological unit consisting of alternating bands, of varying thickness, of pillow basalts and a green/grey sandstone that is of mafic origin, potentially derived from the pillow basalt itself.

It shows good cross-bedding and rare ripple structures indicating a tidal depositional environment.

There is a large scale syncline running NNE-SSW, that extends straight through the summit of Moel yr Ogof and can be seen clearly, in the mountain's profile, when taking the path up to the Hebog ridge from the South.

Owain Glyndŵr's cave can be found on the cliff at the eastern flank of the mountain.