Anatase is an ore of titanium dioxide. The first crystal was measured and described by Tutton - "Crystallography and Practical Crystal Measurement", AEH Tutton, Macmillan and Co. Ltd, London, London, 1911, Chapter XIV, pages 212 - 226. https://archive.org/details/crystallographyp00tuttuoft The model was constructed to resemble figure 162 (p. 212). A second crystal model was constructed from Figure 36, Volume 1, table 27 in Goldschmidt's "Atlas Der Krystallformen Tafeln" https://archive.org/stream/atlasderkrystalltaf01gold#page/27/ An attempt was made to generalize the openSCAD code; it might be useful for other tetragonal or orthorhombic crystals