Windhoekite is a rare phyllosilicate mineral found primarily in alkaline igneous environments. It typically forms as thin, pearly white crusts or delicate aggregates on the surfaces of associated minerals like sodalite in pegmatite cavities.

Hardness

Mohs

Luster

Pearly

Streak

White

Transparency

Translucent

mineralrareSmectite Group family

Windhoekite

Hardness: 2
Luster: Pearly
Streak: White
Transparency: Translucent

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Is this windhoekite?

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

Often confused with

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

mineral

Nontronite

Mohs 1.5-2

How to tell apart: Streak differs — Windhoekite leaves white, Nontronite leaves yellow; luster reads pearly on Windhoekite and dull on Nontronite.

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Often found alongside windhoekite

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

All properties

Chemical formula: Na₄Ca₂Fe³⁺₂Si₁₆O₄₀(OH)₄·12H₂O
Mohs hardness: 2
Density: 2.1 g/cm³
Colors: White Brownish White
Streak: White
Luster: Pearly
Transparency: Translucent
Crystal system: Monoclinic
Crystal habit: Platy Crystals, Crusts
Cleavage: Perfect
Rarity: Rare
Uses: Collector
Host rock: Nepheline Syenite Pegmatites
Typical price: $50-300 per specimen

Where rockhounds find windhoekite

Classic worldwide localities

Aris Quarries, Namibia

Field-hunting tip

Look in nepheline syenite pegmatites country — that is the host setting where windhoekite typically forms. If you start seeing sodalite, aegirine, arfvedsonite in float, you are in the right ground. Field specimens usually show a platy crystals, crusts habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify windhoekite?+

Mohs hardness is 2. It typically shows a pearly luster. The streak is white. Common colors include white, brownish white.

Where is windhoekite found?+

Notable localities include Aris Quarries, Namibia.

How much is windhoekite 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 windhoekite?+

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

What minerals are found with windhoekite?+

Windhoekite commonly co-occurs with Sodalite, Aegirine, Arfvedsonite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does windhoekite form in?+

Windhoekite typically forms in nepheline syenite pegmatites. Working float back to the host body is the standard way to chase a fresh occurrence.

What is windhoekite used for?+

Windhoekite is used in collector.

Find windhoekite on the map

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