Wilhelmgümbelite is a rare secondary phosphate mineral typically found as a result of the alteration of triphylite in granitic pegmatites. Collectors should look for small, delicate platy crystals or radiating sprays in the cavities of weathered phosphate zones. It is named in honor of the German geologist Wilhelm von Gümbel.

Hardness

3-4

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrareHopeite Group family

Wilhelmgümbelite

Hardness: 3-4
Luster: Vitreous
Streak: White
Transparency: Transparent

Is this wilhelmgümbelite?

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 wilhelmgümbelite with a known reference. Wilhelmgümbelite sits at Mohs 3-4 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Wilhelmgümbelite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Wilhelmgümbelite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: colorless, white, pale yellow.
5
Look at form & habit
Crystal system: triclinic. Typical habit: platy crystals, radial aggregates, crusts.

Often confused with

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

Often found alongside wilhelmgümbelite

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

All properties

Chemical formula: ZnFe²⁺(PO₄)₂·4H₂O
Mohs hardness: 3-4
Density: 3.1-3.2 g/cm³
Colors: Colorless White Pale Yellow
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Triclinic
Crystal habit: Platy Crystals, Radial Aggregates, Crusts
Cleavage: Perfect On {010}
Rarity: Rare
Uses: Collector
Host rock: Phosphate-rich Granitic Pegmatites
Typical price: $50-500 thumbnail specimens

Where rockhounds find wilhelmgümbelite

Classic worldwide localities

Hagendorf-South Pegmatite, Germany
Tip Top Mine, South Dakota, USA

Field-hunting tip

Look in phosphate-rich granitic pegmatites country — that is the host setting where wilhelmgümbelite typically forms. If you start seeing triphylite, sicklerite, hureaulite in float, you are in the right ground. Field specimens usually show a platy crystals, radial aggregates, crusts habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify wilhelmgümbelite?+

Mohs hardness is 3-4. It typically shows a vitreous luster. The streak is white. Common colors include colorless, white, pale yellow.

Where is wilhelmgümbelite found?+

Notable localities include Hagendorf-South Pegmatite, Germany; Tip Top Mine, South Dakota, USA.

How much is wilhelmgümbelite worth?+

Typical asking prices fall in the range of $50-500 thumbnail specimens. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like wilhelmgümbelite?+

Wilhelmgümbelite is most often confused with Hopeite, Parahopeite, Phosphophyllite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with wilhelmgümbelite?+

Wilhelmgümbelite commonly co-occurs with Triphylite, Sicklerite, Hureaulite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does wilhelmgümbelite form in?+

Wilhelmgümbelite typically forms in phosphate-rich granitic pegmatites. Working float back to the host body is the standard way to chase a fresh occurrence.

What is wilhelmgümbelite used for?+

Wilhelmgümbelite is used in collector.

Find wilhelmgümbelite on the map

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