Montebrasite is a lithium-rich phosphate mineral occurring primarily in granitic pegmatites. It is often found as massive, cleavable blocks and is visually indistinguishable from amblygonite without chemical analysis, as they form a continuous solid solution series.

Hardness

5.5-6

Mohs

Luster

Vitreous

Streak

White

Transparency

Translucent

mineraluncommonAmblygonite Group family

Montebrasite

Hardness: 5.5-6
Luster: Vitreous
Streak: White
Transparency: Translucent

Is this montebrasite?

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 montebrasite with a known reference. Montebrasite sits at Mohs 5.5-6, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Montebrasite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Montebrasite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: white, colorless, yellow, greenish, gray.
5
Look at form & habit
Crystal system: triclinic. Typical habit: massive, thick tabular crystals.

Often confused with

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

How to tell apart: Quartz is the harder of the two (Mohs 7 vs. 5.5-6).

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Often found alongside montebrasite

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

All properties

Chemical formula: LiAlPO₄(OH)
Mohs hardness: 5.5-6
Density: 3.0-3.1 g/cm³
Colors: White Colorless Yellow Greenish Gray
Streak: White
Luster: Vitreous
Transparency: Translucent
Crystal system: Triclinic
Crystal habit: Massive, Thick Tabular Crystals
Cleavage: Perfect Basal
Rarity: Uncommon
Uses: Collector, Lithium Source
Host rock: Granite Pegmatites
Typical price: $10-100 per specimen

Where rockhounds find montebrasite

Classic worldwide localities

Montebras, France
Minas Gerais, Brazil
Newry, Maine, USA
Black Hills, South Dakota, USA
Karibib, Namibia

Field-hunting tip

Look in granite pegmatites country, the host setting where montebrasite typically forms. If you start seeing lepidolite, tourmaline, cassiterite in float, you are in the right ground. Field specimens usually show a massive, thick tabular crystals habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify montebrasite?+

Mohs hardness is 5.5-6. It typically shows a vitreous luster. The streak is white. Common colors include white, colorless, yellow, greenish.

Where is montebrasite found?+

Notable localities include Montebras, France; Minas Gerais, Brazil; Newry, Maine, USA; Black Hills, South Dakota, USA; Karibib, Namibia.

How much is montebrasite worth?+

Typical asking prices fall in the range of $10-100 per specimen. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like montebrasite?+

Montebrasite is most often confused with Amblygonite, Feldspar, Quartz. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with montebrasite?+

Montebrasite commonly co-occurs with Lepidolite, Tourmaline, Cassiterite, Quartz, Apatite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does montebrasite form in?+

Montebrasite typically forms in granite pegmatites. Working float back to the host body is the standard way to chase a fresh occurrence.

What is montebrasite used for?+

Montebrasite is used in collector, lithium source.

Find montebrasite on the map

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