The precipitation of inorganic crystals from body fluid requires (A) elimination of the macromolecules that inhibit for crystal formation, (B) sufficient supersaturation of the relevant ions, and (C) local restriction of molecular movement. All of these must be accomplished within a space of several nanometers width. Such a nanospace excludes most peptides and oligosaccharides (A). The relaxation time of the outer layer of hydration water (nano second order) on the nanospace wall is 1,000 times longer than that of free water (pico second order). This means that the structure temperature of vicinal water is low, thus the solubilities of calcium ions and phosphate ions are reduced (B,C). Stable ion clusters are formed easier in the nanospace than in the bulk water. The 5-6 nm space in which 3 nm thick hydroxyapatite crystallites can exist should be called critical space. The critical space should be formed according to the fibril diameter and disposition of the fibril or by deployment into the filaments, and by microtubular and lamellar structures.