Laurentthomasite is a rare beryllium-bearing silicate discovered in the pegmatites of Madagascar. It typically forms attractive blue to blue-green prismatic crystals that are highly sought after by mineral collectors due to their extreme scarcity.

Hardness

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrareMilarite-Osumilite Group family

Laurentthomasite

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

Is this laurentthomasite?

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 laurentthomasite with a known reference. Laurentthomasite 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. Laurentthomasite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Laurentthomasite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: blue, blue-green.
5
Look at form & habit
Crystal system: hexagonal. Typical habit: prismatic crystals.

Often confused with

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

mineral

Beryl

Mohs 7.5-8

How to tell apart: Beryl is the harder of the two (Mohs 7.5-8 vs. 6).

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

Compare →

Often found alongside laurentthomasite

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

All properties

Chemical formula: Mg₂K(Be₂Al)Si₁₂O₃₀
Mohs hardness: 6
Density: 2.65 g/cm³
Colors: Blue Blue-green
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Hexagonal
Crystal habit: Prismatic Crystals
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Pegmatites
Typical price: $100-500 thumbnail

Where rockhounds find laurentthomasite

Classic worldwide localities

Madagascar
Itrongay

Field-hunting tip

Look in pegmatites country, the host setting where laurentthomasite typically forms. If you start seeing quartz, microcline, phlogopite in float, you are in the right ground. Field specimens usually show a prismatic crystals habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify laurentthomasite?+

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

Where is laurentthomasite found?+

Notable localities include Madagascar; Itrongay.

How much is laurentthomasite worth?+

Typical asking prices fall in the range of $100-500 thumbnail. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like laurentthomasite?+

Laurentthomasite is most often confused with Beryl, Osumilite, Cordierite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with laurentthomasite?+

Laurentthomasite commonly co-occurs with Quartz, Microcline, Phlogopite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does laurentthomasite form in?+

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

What is laurentthomasite used for?+

Laurentthomasite is used in collector.

Find laurentthomasite on the map

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