[German Kieselguhr, obsolete spelling of Kieselgur : Kiesel, pebble (from Middle High German kisel, from Old High German kisil, from Germanic *kisilaz : Germanic *kis-, gravel; probably akin to Lithuanian žiezdra, grain of sand + Germanic *-ilaz, diminutive suffix) + Gur, Guhr, ferment, earthy deposit from water (from gären, to ferment, blend of Middle High German jësan, from Old High German and Middle High German *jern, to cause to ferment, from Old High German jerian; see yes- in the Appendix of Indo-European roots).]