Stefanweissite is an extremely rare phosphate mineral known primarily from the Gun Claim in the Yukon. It typically forms as small, yellowish-brown platy crystals in association with other rare phosphate species in complex hydrothermal deposits.

Hardness

4.5

Mohs

Luster

Vitreous

Streak

White

Transparency

Translucent

mineralrareGorceixite Group family

Stefanweissite

Hardness: 4.5
Luster: Vitreous
Streak: White
Transparency: Translucent

Is this stefanweissite?

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 stefanweissite with a known reference. Stefanweissite sits at Mohs 4.5, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Stefanweissite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Stefanweissite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: yellow, yellowish-brown.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: platy crystals.

Often confused with

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

How to tell apart: Stefanweissite is noticeably harder (Mohs 4.5 vs. 2); streak differs, so Stefanweissite leaves white, Schulenbergite leaves pale green; luster reads vitreous on Stefanweissite and pearly on Schulenbergite.

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Often found alongside stefanweissite

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

All properties

Chemical formula: BaV₂³⁺(PO₄)₂(OH)₂·H₂O
Mohs hardness: 4.5
Density: 3.55 g/cm³
Colors: Yellow Yellowish-brown
Streak: White
Luster: Vitreous
Transparency: Translucent
Crystal system: Monoclinic
Crystal habit: Platy Crystals
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Hydrothermal Veins in Shales
Typical price: $100-500+ for micro specimens

Where rockhounds find stefanweissite

Classic worldwide localities

Gun Claim, Yukon, Canada

Field-hunting tip

Look in hydrothermal veins in shales country, the host setting where stefanweissite typically forms. If you start seeing vauxite, paravauxite, wardite in float, you are in the right ground. Field specimens usually show a platy crystals habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify stefanweissite?+

Mohs hardness is 4.5. It typically shows a vitreous luster. The streak is white. Common colors include yellow, yellowish-brown.

Where is stefanweissite found?+

Notable localities include Gun Claim, Yukon, Canada.

How much is stefanweissite worth?+

Typical asking prices fall in the range of $100-500+ for micro specimens. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like stefanweissite?+

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

What minerals are found with stefanweissite?+

Stefanweissite commonly co-occurs with Vauxite, Paravauxite, Wardite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does stefanweissite form in?+

Stefanweissite typically forms in hydrothermal veins in shales. Working float back to the host body is the standard way to chase a fresh occurrence.

What is stefanweissite used for?+

Stefanweissite is used in collector.

Find stefanweissite on the map

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