Brannerite is a rare uranium titanium oxide mineral typically found in granitic pegmatites and hydrothermal environments. It usually appears as black, prismatic crystals that often suffer from metamictization, making them appear dull or earthy over time.
Is this brannerite?
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 brannerite with a known reference. Brannerite sits at Mohs 4.5-5.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: dark greenish brown to yellowish brown.
- 3Read the lusterHold the specimen under a strong light. Luster: pitchlike to vitreous when fresh, resinous to dull when altered.
- 4Match the color rangeCompare against the expected color range: black, brown, brown green, yellow, yellow brown.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: crystalline, metamict, prismatic.
Often confused with
Brannerite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Brannerite leaves dark greenish brown to yellowish brown, Allanite leaves gray; luster reads pitchlike to vitreous when fresh, resinous to dull when altered on Brannerite and submetallic on Allanite.
How to tell apart: Streak differs, so Brannerite leaves dark greenish brown to yellowish brown, Euxenite-(Y) leaves yellowish, grayish, or reddish brown; luster reads pitchlike to vitreous when fresh, resinous to dull when altered on Brannerite and brilliant submetallic, waxy to resinous on fractures on Euxenite-(Y).
Often found alongside brannerite
Minerals reported to co-occur with brannerite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- UTi₂O₆
- Mohs hardness
- 4.5-5.5
- Density
- 4.5-5.4 g/cm³
- Streak
- Dark greenish brown to yellowish brown
- Luster
- Pitchlike to vitreous when fresh, resinous to dull when altered
- Transparency
- Opaque, transparent in very thin fragments
- Crystal system
- Monoclinic
- Crystal habit
- Crystalline, metamict, prismatic
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector, Ore of uranium
- Host rock
- A primary mineral in granite pegmatite and in granitic gneiss; in silicified pebble conglomerates; in hydrothermal quartz and calcite veins; detrital in placers
Where rockhounds find brannerite
Classic worldwide localities
- Kelly Gulch, Custer Co., Idaho, USA
- San Bernardino Mountains, San Bernardino Co., and about ten km south of Coleville, Mono Co., California, USA
- California mine, Chaffee Co., Colorado, USA
- Penn Haven Junction, Carbon Co., Pennsylvania, USA
- Blind River-Elliot Lake district, Ontario, and at Eldorado, Saskatchewan, Canada
- Hornachuelos, Fuente Obejuna, and El Cabril, Cordoba, Spain
Field-hunting tip
Where it forms: A primary mineral in granite pegmatite and in granitic gneiss; in silicified pebble conglomerates; in hydrothermal quartz and calcite veins; detrital in placers. If you start seeing uraninite, gold, rutile in float, you are in the right ground. Typical habit: crystalline, metamict, prismatic. Train your eye for that shape before scanning the outcrop.
Common questions
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Find brannerite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
