Ghost World — John Russell Fearn

Continuing their interstellar voyages, the Cosmic Crusaders find a strange planet whose inhabitants are held in thrall by a baleful hypnotic influence, reinforced by a gigantic luminescent "face" in the sky, stretching across thousands of miles of space. The servitor race are reduced to a zombie-like state, as they mine two kinds of mineral rocks, leaving them in carefully separated cairns on the surface of the planet. Periodically the rocks are collected by their alien overlords. The Golden Amazon and her fellow Crusaders soon become locked in a struggle to the death to uncover the mystery of the rock mining and overthrow a cosmic tyranny. Another action-packed scientific adventure in the ongoing saga of the Golden Amazon!