Anatase
Anatase, TiO2, is tetragonal: hardness 5.5 to 6, density 3.79 to 3.97, white to pale yellow streak. Its pyramid faces rise 68.3° from the base; rutile’s 32.8°.
Anatase is titanium dioxide, TiO2 on the IMA list (A, 1962 s.p., France): tetragonal, typically in acute dipyramids, hardness 5.5 to 6, density 3.79 to 3.97, streak white to pale yellow, uniaxial negative. Worked from the sheets’ cells, its {011} faces rise 68.3° from the base, rutile’s {101} only 32.8°. A 20.00 g piece reads 14.72 to 14.96 g in water.
In short
- The species. The Handbook of Mineralogy sheet gives TiO2, tetragonal, crystals typically acute dipyramidal {011}, often highly modified, also tabular on {001}, to 3.75 cm; cleavage perfect on {001} and {011}; hardness 5.5 to 6; density 3.79 to 3.97; brown, yellow, reddish brown, indigo or black, with a white to pale yellow streak and adamantine lustre. The September 2026 IMA-CNMNC Master List lists it as TiO2, status A, 1962 s.p., France.
- The extension check. The sheet derives the name from the Greek for extension, for the greater length of the usual pyramid. Worked from the cell, a 3.7845 and c 9.5143 Å, anatase’s {011} faces rise 68.3° from the base and meet at the apex at 43.4°. Rutile’s {101} faces, from its cell, rise 32.8° and meet at 114.4°: a sharp spire against a low roof.
- The cell check. Divide each sheet’s cell volume by the formula units in it: anatase 34.07 ų per TiO2, brookite 32.20, rutile 31.22. Anatase gives each TiO2 9.1% more room than rutile, which is why it is the lightest of the three: computed from its cell, 3.893, against the sheet’s 3.89. Documented failure: brookite’s cell gives 4.118, not the sheet’s printed 4.133.
- Five TiO2 rows, three on the sheets. A script over the IMA list finds 5 rows written TiO2: akaogiite, anatase, brookite, rutile and srilankite, as on rutile. The sheets cover the three a collector meets. A 20.00 g piece reads 14.72 to 14.96 g in water as anatase, 15.10 to 15.22 g as brookite and 15.27 g as rutile. How to tell the pair apart is on anatase vs rutile.
- Uses and magnet. The USGS Mineral Commodity Summaries 2026, titanium mineral concentrates says world resources of anatase, ilmenite and rutile total more than 2 billion tons; its production figures are for ilmenite and rutile only, so this page makes no use claim for anatase. USGS’s one anatase sample was not pulled at 1.70 amp, the separator’s top; that is set out on is anatase magnetic.
| Name | System (sheet) | Cell (Å), Z | Volume per TiO2 | Density from cell | Density (sheet, calc. / meas.) | Usual pyramid, rise from base | 20.00 g piece in water |
|---|---|---|---|---|---|---|---|
| Anatase | Tetragonal, I41/amd | a 3.7845, c 9.5143; Z 4 | 34.07 ų | 3.893 | 3.89 / 3.79–3.97 | {011}, 68.3°; apex 43.4° | 14.72–14.96 g |
| Brookite | Orthorhombic, Pcab | a 5.4558, b 9.1819, c 5.1429; Z 8 | 32.20 ų | 4.118 | 4.133 / 4.08–4.18 | {111}, n.c. | 15.10–15.22 g |
| Rutile | Tetragonal, P42/mnm | a 4.5937, c 2.9587; Z 2 | 31.22 ų | 4.248 | 4.25 / 4.23 | {101}, 32.8°; apex 114.4° ({111}, 42.3°) | 15.27 g |
What is anatase? Titanium dioxide in steep pyramids
Anatase is TiO2, the tetragonal titanium dioxide that the sheet says typically grows as acute dipyramids. The Handbook of Mineralogy anatase sheet gives point group 4/m 2/m 2/m and space group I41/amd: crystals typically acute dipyramidal {011}, often highly modified; obtuse pyramidal or tabular on {001}; less commonly prismatic on [001] with {110} and {010}, to 3.75 cm. Twinning is rare, on {112}. Cleavage is perfect on {001} and {011}, the fracture subconchoidal, the tenacity brittle; hardness 5.5 to 6, VHN 616–698; measured density 3.79 to 3.97 against a calculated 3.89. The sheet adds that pyramidal crystals may appear opaque because of total reflection.
Colour and optics. Brown, pale yellow or reddish brown, indigo, black; pale green, pale lilac, gray, rarely nearly colorless. Streak white to pale yellow; lustre adamantine to splendent, metallic. Uniaxial (−), anomalously biaxial in deeply colored crystals, with ω 2.5612 and ε 2.4880, read from the rendered sheet because the text layer drops the ε. The birefringence, worked, is 0.0732.
What the IMA list records. The September 2026 list gives anatase TiO2, status A, with 1962 s.p., an action by special procedure, and France as the country of first description. The sheet marks no type locality; it places type material at the Natural History Museum, Paris. On standard atomic weights TiO2 is 59.93% titanium; the sheet’s Rio Cipo, Minas Gerais, analysis, at 98.98 wt% TiO2, works out at 59.32% titanium.
Why is it called anatase? The extension check
The name is a description of the pyramid, and the cell data put a number on it. The sheet derives anatase from the Greek for extension, for the greater length of the usual pyramid compared with other tetragonal minerals. For a tetragonal face (hkl), the angle at which it rises from the base is arctan((c/a) × √(h² + k²) / l). Anatase’s cell is a 3.7845, c 9.5143 Å, c/a 2.514, so its {011} faces rise 68.3°, and two opposite faces meet at the apex at 43.4° in a section through the c axis.
Rutile, worked the same way. The rutile sheet’s cell is a 4.5937, c 2.9587 Å, c/a 0.644. Its prisms are terminated by {101} or {111}: {101} faces rise 32.8°, meeting at 114.4°; {111} faces rise 42.3°. Anatase’s usual pyramid is a spire, rutile’s termination a low roof. All forms quoted here were read from the rendered sheets.
Documented failure: habit crosses over. The rutile sheet says rutile is also equant and rarely dipyramidal; the anatase sheet says anatase is also obtuse pyramidal or tabular on {001}, and less commonly prismatic. The angle describes a sheet’s usual form; it says nothing about a tabular anatase, a broken prism or a grain. The other separations, with their own failures, are on anatase vs rutile.
Why is anatase lighter than rutile? The cell check
Anatase packs the same formula into more space. Dividing each sheet’s cell volume by Z, the formula units per cell: anatase 136.27 ų / 4 = 34.07 ų per TiO2; the brookite sheet’s 257.63 ų / 8 = 32.20; rutile 62.43 ų / 2 = 31.22. Anatase gives each TiO2 9.1% more room than rutile and 5.8% more than brookite. Same mass, more volume, lower density.
The density, recomputed. Density from a cell is Z × 79.865 / (6.02214 × 10²³ × V), with V in cm³. That gives anatase 3.893, matching the sheet’s calculated 3.89, and rutile 4.248, matching 4.25. Documented failure: brookite’s printed cell gives 4.118, while its sheet prints a calculated 4.133, 0.015 higher. The sheet does not say which cell or composition its figure used, and this page does not resolve it. The measured ranges keep the order: anatase 3.79 to 3.97, brookite 4.08 to 4.18, rutile 4.23.
On a balance. At those measured densities a 20.00 g solid piece reads 14.72 to 14.96 g in water as anatase, 15.10 to 15.22 g as brookite and 15.27 g as rutile: the same figures as the TiO2 ladder on rutile, which is not repeated here. The method is on how to measure specific gravity at home.
Where is anatase found, and is it used for anything?
Where it is found. The sheet calls anatase a very wide-spread mineral, of which only a few occurrences can be noted: Alpine veins throughout the Swiss, French, Italian and Tirolian Alps, with large crystals from Binn, Valais, and Cavradi, Tavetsch, Graubünden; LaGrave, Hautes-Alpes, and Bourg d’Oisans, Isère, France; Kragerø, and fine crystals from Hardangervidda, Slidre and Gudbrandsdalen, Norway; the Khodrovy Mountains, Sakha, Russia; the Virtuous Lady mine, Devon; Fron Oleu near Tremadog, Wales; carbonatite deposits aggregating 500 million tons in Minas Gerais and Pará, Brazil; Burke Co., North Carolina, Buckingham Co., Virginia, Quincy, Massachusetts, and Placerville, California; Sherbrooke Township, Nova Scotia, and Henvey Township, Ontario.
How it forms and what it grows with. Usually secondary, derived from other titanium-bearing minerals; in Alpine veins, derived from the enclosing gneisses or schists by hydrothermal solutions; in igneous and metamorphic rocks, pegmatites and a carbonatite; a common detrital mineral. The Association line names brookite, rutile, titanite, ilmenite, titanian magnetite, hematite and quartz.
Uses, as far as a fetched source goes. The USGS Mineral Commodity Summaries 2026, titanium mineral concentrates says ilmenite accounts for about 90% of the world’s consumption of titanium minerals and that world resources of anatase, ilmenite and rutile total more than 2 billion tons. Its production and trade figures are for ilmenite and rutile; anatase has no line of its own, and this page claims no use for it. USGS’s one anatase sample stayed behind at 1.70 amp on its magnetic separator, set out on is anatase magnetic. The rest of the reference section is at the species index. We hold no catalogue and nothing here is offered for sale; the wanted list is the only commercial route.