Mourite is an extremely rare molybdenum mineral typically found in hydrothermal veins associated with oxidized molybdenite deposits. It is best known for its striking deep blue to violet fibrous or needle-like crystal clusters, which make it highly sought after by systematic mineral collectors.
Is this mourite?
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 mourite with a known reference. Mourite sits at Mohs ~3, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: blue-violet.
- 3Read the lusterHold the specimen under a strong light. Luster: adamantine.
- 4Match the color rangeCompare against the expected color range: violet.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: fan shaped, fibrous, radial.
Often confused with
Mourite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Mourite leaves blue-violet, Molybdite leaves white.
How to tell apart: Ilsemannite is the harder of the two (Mohs 5.5-6 vs. ~3); streak differs, so Mourite leaves blue-violet, Ilsemannite leaves pale blue; luster reads adamantine on Mourite and dull on Ilsemannite.
Often found alongside mourite
Minerals reported to co-occur with mourite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (UO₂)(Mo⁶⁺)₅O₁₆·5H₂O
- Mohs hardness
- ~3
- Density
- 3.78-4.12 g/cm³
- Colors
- Streak
- Blue-violet
- Luster
- Adamantine
- Transparency
- Opaque to translucent
- Crystal system
- Monoclinic
- Crystal habit
- Fan shaped, fibrous, radial
- Cleavage
- {100}, pronounced
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In the oxidized zone of a U–Mo deposit (Kyzylsai deposit, Kazakhstan); in a sandstone-hosted uranium deposit (Boso-Hackney prospect, Texas, USA)
Where rockhounds find mourite
Classic worldwide localities
- Boso-Hackney prospect, about 19 km southwest of Falls City, Karnes Co., Texas, USA
- Kyzylsai Mo–U deposit, Chu-Ili Mountains, southwestern Balkhash region, Kazakhstan
Field-hunting tip
Where it forms: In the oxidized zone of a U–Mo deposit (Kyzylsai deposit, Kazakhstan); in a sandstone-hosted uranium deposit (Boso-Hackney prospect, Texas, USA). If you start seeing uraninite, molybdenite, jordisite in float, you are in the right ground. Typical habit: fan shaped, fibrous, radial. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify mourite?+
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Is mourite safe to handle?+
What rocks look like mourite?+
What minerals are found with mourite?+
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Find mourite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
