To obtain inorganic compounds capable of developing mineral function in vivo by metabolism of Bacillus natto and Bacillus subtilis and contributing for health maintenance by culturing Bacillus natto and Bacillus subtilis in a liquid culture medium on which Bacillus natto and Bacillus subtilis are parasitic or in which these bacteria are inoculated.

An inorganic crystal is obtained by metabolizing Bacillus natto and Bacillus subtilis (hereinafter referred to as Bacillus subtilis or the like) in a liquid culture medium in which Bacillus subtilis or the like are parasitic or in which Bacillus subtilis or the like are inoculated. Furthermore, the crystal has the following physicochemical properties. Elemental analysis: N 5.05%, C 0.47%, H 5.85%. Elements detected by emission spectrochemical analysis: Mg and P contents: larger amounts; Ca, Mn and Fe contents: small amounts; Si content: smaller amount; Na content: a trace amount. Color, transparent in water and translucent or white in air. Solubility, insoluble in water, an aqueous alkali solution, alcohols, etc., and readily soluble in an aqueous acid solution. An inorganic acid salt (BYC), by-product (BBP), a mixture thereof (BAHC) and a substance whose ion form is similar to that of BTC and BAHC are obtained by dissolving the inorganic substances into hydrochloric acid, pouring these substances into water, treating the liquid with activated carbon, filtering the liquid and drying the filtrate.