Steigerite is a rare secondary vanadium mineral that typically forms as bright, lemon-yellow powdery coatings or encrustations on sandstone. It is most commonly found in the Colorado Plateau region of the United States, usually associated with other vanadate minerals.
Is this steigerite?
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 steigerite with a known reference. Steigerite sits at Mohs 2.5-3, 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: waxy in compact aggregates.
- 4Match the color rangeCompare against the expected color range: canary yellow, olive green.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: pulverulent.
Often confused with
Steigerite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Steigerite leaves yellow, Carnotite leaves strontian-yellow; luster reads waxy in compact aggregates on Steigerite and dull, earthy; silky when crystalline on Carnotite.
How to tell apart: Streak differs, so Steigerite leaves yellow, Tyuyamunite leaves light yellow; luster reads waxy in compact aggregates on Steigerite and adamantine, pearly on {001}, may be dull to waxy if massive on Tyuyamunite.
Often found alongside steigerite
Minerals reported to co-occur with steigerite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Al(VO₄)·3H₂O
- Mohs hardness
- 2.5-3
- Density
- 2.52-2.58 g/cm³
- Colors
- Streak
- Yellow
- Luster
- Waxy in compact aggregates
- Transparency
- Semitransparent
- Crystal system
- Monoclinic
- Crystal habit
- Pulverulent
- Cleavage
- Perfect on {010}; fair on {100} and {100}
- Fluorescence
- Fluorescent
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In U–V deposits impregnating sandstone (Gypsum Valley, Colorado, USA); a weathering product in vanadium-rich schists (Kara-Tau Mountains, Kazakhstan)
Where rockhounds find steigerite
Classic worldwide localities
- Sullivan Brothers claim, Cypsum Valley, San Miguel County, Colorado, USA (type locality)
Field-hunting tip
Where it forms: In U–V deposits impregnating sandstone (Gypsum Valley, Colorado, USA); a weathering product in vanadium-rich schists (Kara-Tau Mountains, Kazakhstan). If you start seeing fervanite, corvusite, gypsum in float, you are in the right ground. Typical habit: pulverulent. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify steigerite?+
Where is steigerite found?+
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What rocks look like steigerite?+
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Find steigerite on the map
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