Brookite is a distinct titanium dioxide polymorph known for its unique orthorhombic crystal structures, often appearing as flattened, brownish-black tabular crystals. It is most prized by collectors for its occurrence in alpine-type clefts and hydrothermal settings where it forms alongside its polymorphs, rutile and anatase. Collectors should look for sharp, blade-like crystals in pockets of igneous and metamorphic rocks.
Is this brookite?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch brookite with a known reference. Brookite sits at Mohs 5.5-6, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white to grayish white or yellowish white.
- 3Read the lusterHold the specimen under a strong light. Luster: metallic adamantine to submetallic.
- 4Match the color rangeCompare against the expected color range: reddish-brown, brown, black, yellowish-brown, light brown, dark brown, dark reddish brown, orange.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: platy, tabular.
Often confused with
Brookite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Brookite leaves white to grayish white or yellowish white, Rutile leaves pale brown, yellowish brown; gray, greenish black with high nb–ta; luster reads metallic adamantine to submetallic on Brookite and adamantine to submetallic on Rutile.
How to tell apart: Luster reads metallic adamantine to submetallic on Brookite and adamantine to splendent, metallic on Anatase.
How to tell apart: Streak differs, so Brookite leaves white to grayish white or yellowish white, Ilmenite leaves black to reddish brown.
Often found alongside brookite
Minerals reported to co-occur with brookite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- TiO₂
- Mohs hardness
- 5.5-6
- Density
- 4.08-4.18 g/cm³
- Streak
- White to grayish white or yellowish white
- Luster
- Metallic adamantine to submetallic
- Transparency
- Opaque to translucent, transparent in thin fragments
- Crystal system
- Orthorhombic
- Crystal habit
- Platy, tabular
- Cleavage
- {120}, indistinct; {001}, in traces
- Rarity
- Uncommon
- Uses
- Collector, Scientific study
- Host rock
- An accessory mineral in alpine veins in gneiss and schist; in contact metamorphic zones and hydrothermal veinlets; a common detrital mineral
Where rockhounds find brookite
1 mapped spotsClassic worldwide localities
- Magnet Cove, Hot Spring Co., Arkansas, USA
- Ellensville, Ulster Co., New York, USA
- Powderhorn, Gunnison Co., Colorado, USA
- Fron Oleu, near Tremadog, Gwynned, Wales
- Bourg d’Oisans, Isère, France
- Maderanthal and Griessertal, Uri, at Salvan, Valais, Switzerland
Field-hunting tip
Where it forms: An accessory mineral in alpine veins in gneiss and schist; in contact metamorphic zones and hydrothermal veinlets; a common detrital mineral. If you start seeing anatase, rutile, titanite in float, you are in the right ground. Typical habit: platy, tabular. Train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Arkansas. Start trip planning there.
Common questions
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Find brookite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
