A chromium-bearing variety of muscovite mica, named after the mineralogist Johann Nepomuk von Fuchs. The deeper the chromium content, the deeper the green.

Found in metamorphic terrain across Brazil, India, and Russia. It has the thin, layered structure typical of mica, and under light, a fine sparkle rises to the surface. Neither metal nor liquid, yet in certain light it briefly resembles both.

Occasionally it hosts crystals of ruby. "Ruby in fuchsite"—red points against a green ground—is two contrasting minerals growing simultaneously from the same host rock. Complementary colours, side by side in nature.