High above the equator, a Chinese satellite holds a fixed gaze over one-third of Earth's surface — not merely as a feat of engineering, but as the visible expression of a quieter, deeper advantage. China's near-total control of the world's gallium supply, a byproduct of its dominance in aluminum refining, has translated into a persistent surveillance capability that the United States has pursued for decades without success. In the competition for technological supremacy, it is sometimes the most unheralded materials — not the grandest designs — that determine who can see, and who remains unsee