This project investigates the identification and characterization of the micro-sized crystalline products formed when inorganic components are rapidly precipitated from solution containing a specific additive component. These precipitations are derived in most instances by homogeneous nucleation and under conditions of large supersaturations, as two solutions are rapidly mixed in a flow-mixing device (Nielson rapid mixing method). To broaden application of the technique, a modification permits use of more soluble systems through secondary nucleation mechanisms. The product crystals are characterized to determine the extent of crystallinity and the uniformity of additive distribution by electron microscope and X-ray methods. The underlying model visualized and employed in devising the experiments is that continuous crystal growth occurs, i.e., the crystal surface is diffuse. The motivation for this work is to produce uniform solid mixtures suitable for several applications, such as raw materials for refractory materials, catalysts, and semiconductor systems. The work also provides insight into the basic mechanisms involved when rapid crystal growth from solution occurs.