Fabianite is a very rare borate mineral typically found in sedimentary evaporite sequences. It is best identified by its association with other borate species and its relatively high hardness for a borate mineral.

Hardness

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrare

Fabianite

Hardness: 6
Luster: Vitreous
Streak: White
Transparency: Transparent

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Is this fabianite?

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 fabianite with a known reference. Fabianite sits at Mohs 6 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Fabianite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Fabianite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: colorless, white.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: tabular crystals, massive.

Often confused with

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

mineral

Danburite

Mohs 7-7.5

How to tell apart: Danburite is the harder of the two (Mohs 7-7.5 vs. 6).

How to tell apart: Fabianite is noticeably harder (Mohs 6 vs. 2-2.5); luster reads vitreous on Fabianite and vitreous to earthy on Borax.

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Often found alongside fabianite

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

All properties

Chemical formula: CaB₃O₅(OH)
Mohs hardness: 6
Density: 2.83 g/cm³
Colors: Colorless White
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Monoclinic
Crystal habit: Tabular Crystals, Massive
Cleavage: Perfect
Rarity: Rare
Uses: Collector
Host rock: Evaporite Deposits
Typical price: $50-300 per specimen

Where rockhounds find fabianite

Classic worldwide localities

Dolores Hidalgo, Mexico
Zechstein formation, Germany

Field-hunting tip

Look in evaporite deposits country — that is the host setting where fabianite typically forms. If you start seeing boracite, danburite, anhydrite in float, you are in the right ground. Field specimens usually show a tabular crystals, massive habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify fabianite?+

Mohs hardness is 6. It typically shows a vitreous luster. The streak is white. Common colors include colorless, white.

Where is fabianite found?+

Notable localities include Dolores Hidalgo, Mexico; Zechstein formation, Germany.

How much is fabianite 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 fabianite?+

Fabianite is most often confused with Danburite, Borax. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with fabianite?+

Fabianite commonly co-occurs with boracite, danburite, anhydrite, gypsum. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does fabianite form in?+

Fabianite typically forms in evaporite deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

What is fabianite used for?+

Fabianite is used in collector.

Find fabianite on the map

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