Abstract: Embodiments of a method for making metal oxides or mixed metal oxides are disclosed. One representative embodiment comprises selecting a substrate for making the metal oxide or mixed metal oxide, contacting a biological system with the substrate material for an effective period of time, and optionally isolating the metal oxide or mixed metal oxide from the biological system. The biological system can be a living organism, or proteins derived from the living organism. Working embodiments used microalgae, specifically diatoms of the class Bacillariophycae, including marine Pennate diatoms, such as Nitzschia and/or Pinnularia diatoms, and Centric diatoms, such as Cyclotella species. The method also can involve post processing a primary or secondary material produced biologically.