Aspedamite is a very rare mineral, one of two natural heteropolyniobates. Its chemical formula (one of the possible formulas) is complex and shows the presence of essential vacancies: []<sub>12</sub>(Fe<sup>3+</sup><sub>2</sub>Fe<sup>2+</sup>)Nb<sub>4</sub>(ThNb<sub>9</sub>Fe<sup>3+</sup><sub>2</sub>Ti<sup>4+</sup>O<sub>42</sub>)(H<sub>2</sub>O)<sub>9</sub>(OH)<sub>3</sub>. Its structure (isometric, space group Im3) is the same as of the second known heteropolyniobate - menezesite. Aspedamite is somewhat similar to another mineral from Norway, peterandresenite, which is a hexaniobate.