Pseudobrookite is a titanium-iron oxide that typically occurs as small, dark, tabular or acicular crystals within cavities of volcanic rocks. It is most easily identified by its distinctive adamantine luster and its association with high-temperature minerals in igneous volcanic environments.
Is this pseudobrookite?
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 pseudobrookite with a known reference. Pseudobrookite sits at Mohs 6, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: reddish brown to ocher-yellow.
- 3Read the lusterHold the specimen under a strong light. Luster: metallic adamantine, may be tarnished iridescent, greasy on fractures.
- 4Match the color rangeCompare against the expected color range: brownish black, reddish brown, black.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: crystalline.
Often confused with
Pseudobrookite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Pseudobrookite leaves reddish brown to ocher-yellow, Hematite leaves cherry-red or reddish brown.
How to tell apart: Streak differs, so Pseudobrookite leaves reddish brown to ocher-yellow, Ilmenite leaves black to reddish brown.
How to tell apart: Streak differs, so Pseudobrookite leaves reddish brown to ocher-yellow, Brookite leaves white to grayish white or yellowish white.
Often found alongside pseudobrookite
Minerals reported to co-occur with pseudobrookite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Fe₂TiO₅
- Mohs hardness
- 6
- Density
- 4.33-4.39 g/cm³
- Streak
- Reddish brown to ocher-yellow
- Luster
- Metallic adamantine, may be tarnished iridescent, greasy on fractures
- Transparency
- Opaque, transparent in thin fragments
- Crystal system
- Orthorhombic
- Crystal habit
- Crystalline
- Cleavage
- {102}, distinct
- Rarity
- Uncommon
- Uses
- Collector, Scientific research
- Host rock
- Typically, formed by pneumatolytic processes in titanium-rich andesite, rhyolite, basalt, etc., and by reactions with xenoliths within these; in lithophysae
Where rockhounds find pseudobrookite
Classic worldwide localities
- Thomas Range, Juab Co., Utah, USA
- Crater Lake, West Klamath Co., and Lemolo Lake, Douglas Co., Oregon, USA
- A number of places in the Black Range, Sierra Co., New Mexico, USA
- Nine Mile Pluton, Marathon County, Wisconsin, USA
- Măgura Uroiului (Aranyer Berg), near Piski, Romania
- Mayen, Eifel district, Germany
Field-hunting tip
Where it forms: Typically, formed by pneumatolytic processes in titanium-rich andesite, rhyolite, basalt, etc., and by reactions with xenoliths within these; in lithophysae. If you start seeing hematite, magnetite, bixbyite in float, you are in the right ground. Typical habit: crystalline. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify pseudobrookite?+
Where is pseudobrookite found?+
What rocks look like pseudobrookite?+
What minerals are found with pseudobrookite?+
What kind of rock does pseudobrookite form in?+
What is pseudobrookite used for?+
Find pseudobrookite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
