Harmunite is an extremely rare calcium iron oxide mineral identified primarily in high-temperature pyrometamorphic rocks. It typically appears as small yellow to yellowish-brown crystals within complex mineral assemblages formed by combustion metamorphism.

Hardness

3.5

Mohs

Luster

Resinous

Streak

Yellow

Transparency

Translucent

mineralrare

Harmunite

Hardness: 3.5
Luster: Resinous
Streak: Yellow
Transparency: Translucent

Is this harmunite?

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 harmunite with a known reference. Harmunite sits at Mohs 3.5 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Harmunite leaves a yellow streak.
3
Read the luster
Hold the specimen under a strong light. Harmunite typically shows a resinous luster.
4
Match the color range
Compare against the expected color range: yellow, yellowish-brown.
5
Look at form & habit
Crystal system: orthorhombic. Typical habit: platy to tabular crystals.

Often confused with

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

mineral

Brownmillerite

Mohs 5-6

How to tell apart: Brownmillerite is the harder of the two (Mohs 5-6 vs. 3.5); streak differs — Harmunite leaves yellow, Brownmillerite leaves brown; luster reads resinous on Harmunite and submetallic on Brownmillerite.

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Often found alongside harmunite

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

All properties

Chemical formula: CaFe₂O₄
Mohs hardness: 3.5
Density: 3.55 g/cm³
Colors: Yellow Yellowish-brown
Streak: Yellow
Luster: Resinous
Transparency: Translucent
Crystal system: Orthorhombic
Crystal habit: Platy to Tabular Crystals
Cleavage: Good
Rarity: Rare
Uses: Collector
Host rock: Pyrometamorphic Rocks
Typical price: expensive

Where rockhounds find harmunite

Classic worldwide localities

Hatrurim Formation, Israel

Field-hunting tip

Look in pyrometamorphic rocks country — that is the host setting where harmunite typically forms. If you start seeing brownmillerite, gehlenite, larnite in float, you are in the right ground. Field specimens usually show a platy to tabular crystals habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify harmunite?+

Mohs hardness is 3.5. It typically shows a resinous luster. The streak is yellow. Common colors include yellow, yellowish-brown.

Where is harmunite found?+

Notable localities include Hatrurim Formation, Israel.

How much is harmunite worth?+

Typical asking prices fall in the range of expensive. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like harmunite?+

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

What minerals are found with harmunite?+

Harmunite commonly co-occurs with brownmillerite, gehlenite, larnite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does harmunite form in?+

Harmunite typically forms in pyrometamorphic rocks. Working float back to the host body is the standard way to chase a fresh occurrence.

What is harmunite used for?+

Harmunite is used in collector.

Find harmunite on the map

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