Yingjiangite is a rare secondary uranium phosphate mineral that typically forms as delicate, bright yellow platy crystals or powdery crusts. It is most notable for its intense fluorescence under ultraviolet light and is primarily found in the oxidized zones of uranium deposits. Due to its radioactive nature, it is strictly a collector's mineral that requires careful storage and handling practices.
Is this yingjiangite?
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 yingjiangite with a known reference. Yingjiangite 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: yellow.
- 3Read the lusterHold the specimen under a strong light. Luster: subadamantine to resinous.
- 4Match the color rangeCompare against the expected color range: yellow, golden yellow.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: aggregates.
Often confused with
Yingjiangite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Yingjiangite leaves yellow, Autunite leaves pale yellow; luster reads subadamantine to resinous on Yingjiangite and vitreous, pearly on {001} on Autunite.
How to tell apart: Streak differs, so Yingjiangite leaves yellow, Uranocircite leaves light yellow; luster reads subadamantine to resinous on Yingjiangite and pearly on Uranocircite.
Often found alongside yingjiangite
Minerals reported to co-occur with yingjiangite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- K₂Ca(UO₂)₇(PO₄)₄(OH)₆·6H₂O
- Mohs hardness
- 3-4
- Density
- 4.15 g/cm³
- Colors
- Streak
- Yellow
- Luster
- Subadamantine to resinous
- Transparency
- Transparent to translucent
- Crystal system
- Orthorhombic
- Crystal habit
- Aggregates
- Cleavage
- Perfect basal
- Fluorescence
- Weak yellow green under SW and LW UV
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A secondary mineral in an oxidized zone of a uranium deposit (Tongbiguan village, China)
Where rockhounds find yingjiangite
Classic worldwide localities
- Tongbiguan village, Yingjiang Co., Yunnan Province, and in the Xiazhuang uranium deposit, Guangdong Province, China
Field-hunting tip
Where it forms: A secondary mineral in an oxidized zone of a uranium deposit (Tongbiguan village, China). If you start seeing studtite, calcurmolite, tengchongite in float, you are in the right ground. Typical habit: aggregates. Train your eye for that shape before scanning the outcrop.
Common questions
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Find yingjiangite on the map
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