# Anatase

- Page: https://taslar.bumba.tr/en/stones/anatase/
- Turkish: Anataz
- Also known as: Octahedrite (old name)
- Kind: Mineral
- Classification: Minerals › Oxides and hydroxides
- Chemical formula: TiO₂
- Crystal system: Tetragonal
- Hardness (Mohs): 5.5–6
- Specific gravity: 3.79–3.97 g/cm³
- Lustre: Adamantine, Metallic
- Transparency: Transparent, Translucent, Opaque
- Colours: brown, pale yellow, reddish brown, indigo, black, pale green, pale lilac, grey
- Streak: White to pale yellow
- Cleavage: Perfect on {001} and {011}
- Fracture: Subconchoidal; brittle
- Value ladder: 2/9 step, Raw material by the tonne
- Last checked: 2026-10-04

Rutile's sibling in titanium dioxide: its sharp, stretched double pyramids turn into rutile when heated.

Anatase is a mineral made of titanium and oxygen (titanium dioxide, TiO₂). It has the same composition as rutile and brookite but a different crystal structure; of these, rutile is the most stable and common. Its crystals are usually sharp, elongated double pyramids with an adamantine or metallic lustre. René Just Haüy named it in 1801 from the Ancient Greek anatasis, “stretching out”, after its elongated crystals.

## How does it form?

Anatase is usually a **secondary** mineral, formed from the alteration of other titanium-bearing minerals. In Alpine-type crevices it crystallises from titanium carried by hot water solutions out of the surrounding gneiss or schist. It also occurs in igneous and metamorphic rocks, pegmatites and carbonatites, and because it is durable it is common as a detrital grain in sands. It occurs with brookite, rutile, titanite, ilmenite, hematite and quartz. Its crystals can grow up to 3.75 cm.

According to the Handbook of Mineralogy, anatase is a very widespread mineral, found at many places in Alpine crevices across the Swiss, French, Italian and Austrian Alps. Binn and Cavradi in Graubünden, Switzerland, yield large crystals; Hardangervidda and Gudbrandsdalen in Norway are also among its known localities.

## What is it used for?

- **Collecting:** Its sharp double-pyramid crystals are sought by collectors.
- **Titanium source:** Large amounts occur in carbonatite deposits in Brazil.
- **Science and technology:** Thin films of titanium dioxide are used on self-cleaning, anti-fog glass that works under ultraviolet light.

## How to recognise it

- Its crystals are usually sharp, elongated double pyramids; sometimes tabular.
- Brown, pale yellow, reddish brown, indigo or black; adamantine or metallic lustre.
- Light-coloured crystals are transparent; dark ones look nearly opaque.
- Hardness 5.5–6; streak white to pale yellow.
- Found in Alpine-type crevices with quartz, rutile, brookite, ilmenite, hematite and titanite.

## Fakes and imitations

- Rutile and brookite have the same composition as anatase (TiO₂); rutile usually forms long prisms or needles, while anatase forms sharp double pyramids. A certain distinction is made in the laboratory.

## What determines its value?

Anatase is valued as a collector's mineral. Collectors look for sharp, lustrous, large double-pyramid crystals, especially from the Binn valley in Switzerland, Oisans in France and Hardangervidda in Norway. Industrial titanium dioxide is mostly supplied from other titanium minerals and by synthesis.

This information is educational, not buying, selling or investment advice. Value varies enormously with quality and treatment.

## Myths and misconceptions

- Myth: Anatase's metallic lustre shows it is pure titanium metal. Fact: Anatase is not a metal but an oxide of titanium with oxygen (TiO₂). Its dark crystals can shine like metal, but its streak is white to pale yellow.

## Curious questions

**Are anatase and rutile the same thing?**

They have the same composition: both are titanium dioxide (TiO₂). But their atoms are arranged differently, so they have different crystal shapes and properties. Four forms of titanium dioxide occur in nature: anatase, rutile, brookite and akaogiite. Rutile is the most stable; anatase turns into rutile when heated.

## Did you know?

- Heated to between 550 and about 1000 °C, anatase turns into the more stable rutile.
- Glass coated with a thin film of titanium dioxide does not fog up and cleans itself under ultraviolet light.
- Some carbonatite deposits in the Brazilian states of Minas Gerais and Pará hold anatase amounting to 500 million tons in total.

## Where is it found?

- Binn valley (Binntal), Valais, Switzerland (Major deposit): Large honey-yellow to brown pyramidal crystals attached to the walls of crevices in gneiss
- Le Bourg-d'Oisans, Isère, France (Known locality): Anatase crystals in crevices in granite and mica schist
- Hardangervidda, Ullensvang, Norway (Known locality): Yields fine crystals, according to the Handbook of Mineralogy

## Sources

- [Anatase](https://en.wikipedia.org/wiki/Anatase), Wikipedia
- [Handbook of Mineralogy: Anatase](https://www.handbookofmineralogy.org/pdfs/anatase.pdf), Mineralogical Society of America


Source: https://taslar.bumba.tr/en/stones/anatase/ · Licence: CC BY-SA 4.0