Brockite is a rare phosphate mineral characterized by its significant thorium content, which makes it noticeably radioactive. It typically appears as earthy, massive crusts or small radiating acicular aggregates in hydrothermal or alkaline igneous environments.
Is this brockite?
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 brockite with a known reference. Brockite sits at Mohs 3-4, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: greasy to vitreous.
- 4Match the color rangeCompare against the expected color range: white, light yellow, dark reddish brown, reddish brown.
- 5Look at form & habitCrystal system: hexagonal. Typical habit: massive, acicular crystals, radial aggregates.
Often confused with
Brockite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside brockite
Minerals reported to co-occur with brockite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Ca,Th,Ce)PO₄·H₂O
- Mohs hardness
- 3-4
- Density
- 3.9 g/cm³
- Streak
- White
- Luster
- Greasy to vitreous
- Transparency
- Translucent to opaque
- Crystal system
- Hexagonal
- Crystal habit
- Massive, acicular crystals, radial aggregates
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A rare accessory mineral in granite and granite pegmatites
Where rockhounds find brockite
1 mapped spotsClassic worldwide localities
- A prospect pit about 1 km east of the Bassick mine, Querida, Wet Mountains, and at the Hardwick mine and Nightingale shaft, Custer Co., Colorado, USA
- Bear Lodge Mountains, Crook Co., Wyoming, USA
- Diamond Creek district, Lemhi Co., Idaho and the Lemhi Pass district, Idaho-, Montana, USA
- Found in Monroe Canyon, Sevier Co., Utah, USA
- Mont Saint-Hilaire, Quebec, Canada
- Kizilcaoren, Turkey
Field-hunting tip
Where it forms: A rare accessory mineral in granite and granite pegmatites. If you start seeing monazite, bastnäsite, xenotime in float, you are in the right ground. Typical habit: massive, acicular crystals, radial aggregates. Train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Utah. Start trip planning there.
Common questions
How do you identify brockite?+
Where is brockite found?+
Can I find brockite in the United States?+
Is brockite safe to handle?+
What rocks look like brockite?+
What minerals are found with brockite?+
What kind of rock does brockite form in?+
What is brockite used for?+
Find brockite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
