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.
Is this laurentthomasite?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch laurentthomasite with a known reference. Laurentthomasite sits at Mohs 6, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: light blue.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: blue, blue-green.
- 5Look at form & habitCrystal system: hexagonal. Typical habit: prismatic crystals.
Often confused with
Laurentthomasite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Beryl is the harder of the two (Mohs 7.5-8 vs. 6); streak differs, so Laurentthomasite leaves light blue, Beryl leaves white.
How to tell apart: Streak differs, so Laurentthomasite leaves light blue, Osumilite leaves blue-gray.
How to tell apart: Cordierite is the harder of the two (Mohs 7-7.5 vs. 6); streak differs, so Laurentthomasite leaves light blue, Cordierite leaves white.
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
- Streak
- Light blue
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Hexagonal
- Crystal habit
- Prismatic crystals
- Cleavage
- Poor on {0001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- pegmatites
Where rockhounds find laurentthomasite
Classic worldwide localities
- Madagascar
- Itrongay
Field-hunting tip
Where it forms: pegmatites. If you start seeing quartz, microcline, phlogopite in float, you are in the right ground. Typical habit: prismatic crystals. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify laurentthomasite?+
Where is laurentthomasite found?+
Is laurentthomasite safe to handle?+
What rocks look like laurentthomasite?+
What minerals are found with laurentthomasite?+
What kind of rock does laurentthomasite form in?+
What is laurentthomasite used for?+
Find laurentthomasite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
