Metamunirite is a rare anhydrous sodium vanadate that typically forms as delicate, acicular, or fibrous colorless sprays within oxidized sandstone. It is most commonly found in the uranium-vanadium mines of the Colorado Plateau, often occurring as an alteration product of other vanadium minerals. Due to its fragility and rarity, it is a specialized specimen for advanced mineral collectors.
Is this metamunirite?
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 metamunirite with a known reference. Metamunirite sits at Mohs 1, 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: vitreous.
- 4Match the color rangeCompare against the expected color range: colorless.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: acicular crystals, fibrous, sprays.
Often confused with
Metamunirite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Luster reads vitreous on Metamunirite and pearly on Munirite.
How to tell apart: Vanoxite is the harder of the two (Mohs 2-3 vs. 1); streak differs, so Metamunirite leaves white, Vanoxite leaves brown black; luster reads vitreous on Metamunirite and metallic on Vanoxite.
Often found alongside metamunirite
Minerals reported to co-occur with metamunirite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- NaVO₃
- Mohs hardness
- 1
- Density
- 2.877 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Semitransparent
- Crystal system
- Orthorhombic
- Crystal habit
- Acicular crystals, fibrous, sprays
- Cleavage
- The fibrous character is probably due to one or more perfect cleavages
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Extremely rare, in cavities in vanadium-bearing sandstone
Where rockhounds find metamunirite
Classic worldwide localities
- Burro and Deremo-Snyder mines, near Slick Rock, San Miguel Co., Colorado, USA
Field-hunting tip
Where it forms: Extremely rare, in cavities in vanadium-bearing sandstone. If you start seeing rossite, metarossite, pascoite in float, you are in the right ground. Typical habit: acicular crystals, fibrous, sprays. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify metamunirite?+
Where is metamunirite found?+
Is metamunirite safe to handle?+
What rocks look like metamunirite?+
What minerals are found with metamunirite?+
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Find metamunirite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
