Stanleyite is a rare hydrated vanadium sulfate mineral typically found as aquamarine-blue to deep cobalt-blue, needle-like crystals or crusts. It forms as a secondary mineral in the oxidation zones of vanadium-rich sulfide deposits. Due to its solubility, it is best kept in a dry environment to prevent dehydration.

Hardness

1-1.5

Mohs

Luster

Vitreous

Streak

White

Transparency

Semitransparent

mineralrare

Stanleyite

Hardness: 1-1.5
Luster: Vitreous
Streak: White
Transparency: Semitransparent

Is this stanleyite?

5-step field check

Run through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.

1
Test the hardness
Try to scratch stanleyite with a known reference. Stanleyite sits at Mohs 1-1.5, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: white.
3
Read the luster
Hold the specimen under a strong light. Luster: vitreous.
4
Match the color range
Compare against the expected color range: blue, deep blue.
5
Look at form & habit
Crystal system: orthorhombic. Typical habit: crystalline, efflorescences.

Often confused with

Stanleyite vs. its common look-alikes, and how to tell them apart in the field.

Often found alongside stanleyite

Minerals reported to co-occur with stanleyite. Spotting these in float or country rock is a strong cue you are in the right ground.

All properties

Chemical formula: VO(SO₄)·6H₂O
Mohs hardness: 1-1.5
Density: 1.95 g/cm³
Colors: Blue Deep blue
Streak: White
Luster: Vitreous
Transparency: Semitransparent
Crystal system: Orthorhombic
Crystal habit: Crystalline, efflorescences
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Initially found on a museum specimen of patronite from a rich vanadium deposit

Where rockhounds find stanleyite

Classic worldwide localities

Minasragra, 46 km from Cerro de Pasco, Peru

Field-hunting tip

Where it forms: Initially found on a museum specimen of patronite from a rich vanadium deposit. If you start seeing patronite, pyrite, potassium alum in float, you are in the right ground. Typical habit: crystalline, efflorescences. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify stanleyite?+

Mohs hardness is 1-1.5. Luster: vitreous. The streak is white. Common colors include blue, deep blue.

Where is stanleyite found?+

Notable localities include Minasragra, 46 km from Cerro de Pasco, Peru.

Is stanleyite safe to handle?+

Stanleyite contains vanadium. Wash your hands afterwards, never grind or breathe the dust, and store it apart from specimens you handle often.

What rocks look like stanleyite?+

Stanleyite is most often confused with Mallardite, Melanterite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with stanleyite?+

Stanleyite commonly co-occurs with Patronite, Pyrite, Potassium alum, Quartz. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does stanleyite form in?+

Where it forms: Initially found on a museum specimen of patronite from a rich vanadium deposit. Working float back to the host body is the standard way to chase a fresh occurrence.

What is stanleyite used for?+

Stanleyite is used in collector.

Find stanleyite on the map

RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.