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

No image

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, so Harmunite leaves yellow, Brownmillerite leaves brown; luster reads resinous on Harmunite and submetallic on Brownmillerite.

Compare →

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, 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.