Gjerdingenite-Fe is a rare member of the complex labuntsovite group typically found as small, sharp prismatic crystals. It is most often identified in the cavities of alkaline pegmatites, requiring microscopic examination for positive field identification due to its similarity to other group members.

Hardness

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrareLabuntsovite Group family

Gjerdingenite-Fe

Hardness: 5
Luster: Vitreous
Streak: White
Transparency: Transparent

Is this gjerdingenite-fe?

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

Often confused with

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

Often found alongside gjerdingenite-fe

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

All properties

Chemical formula: K₂Ca(Fe,Mn)(Ti,Nb)₄(Si₄O₁₂)₂(O,OH)₄·5H₂O
Mohs hardness: 5
Density: 2.8-2.9 g/cm³
Colors: Yellow Brown Orange-brown
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Monoclinic
Crystal habit: Prismatic Crystals
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Alkaline Igneous Rocks
Typical price: $50-300 per specimen

Where rockhounds find gjerdingenite-fe

Classic worldwide localities

Langesundsfjord, Norway
Mont Saint-Hilaire, Canada

Field-hunting tip

Look in alkaline igneous rocks country — that is the host setting where gjerdingenite-fe typically forms. If you start seeing aegirine, microcline, nepheline in float, you are in the right ground. Field specimens usually show a prismatic crystals habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify gjerdingenite-fe?+

Mohs hardness is 5. It typically shows a vitreous luster. The streak is white. Common colors include yellow, brown, orange-brown.

Where is gjerdingenite-fe found?+

Notable localities include Langesundsfjord, Norway; Mont Saint-Hilaire, Canada.

How much is gjerdingenite-fe worth?+

Typical asking prices fall in the range of $50-300 per specimen. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like gjerdingenite-fe?+

Gjerdingenite-Fe is most often confused with Nenadkevichite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with gjerdingenite-fe?+

Gjerdingenite-Fe commonly co-occurs with Aegirine, Microcline, Nepheline, Eudialyte. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does gjerdingenite-fe form in?+

Gjerdingenite-Fe typically forms in alkaline igneous rocks. Working float back to the host body is the standard way to chase a fresh occurrence.

What is gjerdingenite-fe used for?+

Gjerdingenite-Fe is used in collector.

Find gjerdingenite-fe on the map

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