Granite

Granite is a coarse-grained igneous rock that makes up most of the landmasses on Earth.

The creators of the Shore Leave Planet hid their underground complex beneath a shield of granite and another metal alloy that 23rd century Federation sensors were unable to penetrate. 

The headquarters of the Turkana IV Alliance on Turkana IV is located beneath two kilometers of solid granite. 

On Celtris III, there is a sheer granite cliff five hundred meters high in a cave, on the way to the Cardassian base. 

The underground Vidiian base on Avery III is only accessible through tunnels, disguised by force fields that mimic granite walls. 

A Garan mining colony in the Delta Quadrant was excavated from granite.