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

No image

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.

Compare →

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, 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.