Tsilaisite is a rare member of the tourmaline group characterized by its significant manganese content, which gives it a distinct yellow or yellow-brown hue. It is typically found as prismatic crystals within lithium-rich pegmatites, often alongside other tourmaline species. Collectors highly prize it due to its scarcity compared to other more common members of the tourmaline group.

Hardness

7-7.5

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrareTourmaline Group family

Tsilaisite

Hardness: 7-7.5
Luster: Vitreous
Streak: White
Transparency: Transparent

No image

Is this tsilaisite?

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 tsilaisite with a known reference. Tsilaisite sits at Mohs 7-7.5, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Tsilaisite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Tsilaisite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: yellow, yellow-brown, brown.
5
Look at form & habit
Crystal system: trigonal. Typical habit: prismatic crystals.

Often confused with

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

Often found alongside tsilaisite

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

All properties

Chemical formula: NaMn₃Al₆(Si₆O₁₈)(BO₃)₃(OH)₃(OH)
Mohs hardness: 7-7.5
Density: 3.10-3.15 g/cm³
Colors: Yellow Yellow-brown Brown
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Trigonal
Crystal habit: Prismatic Crystals
Cleavage: Indistinct
Rarity: Rare
Uses: Collector
Host rock: Granite Pegmatites
Typical price: $50-500 depending on crystal size and clarity

Where rockhounds find tsilaisite

Classic worldwide localities

Tsilaisina, Madagascar
San Piero in Campo, Elba, Italy
Antananarivo, Madagascar

Field-hunting tip

Look in granite pegmatites country, the host setting where tsilaisite typically forms. If you start seeing quartz, microcline, albite 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 tsilaisite?+

Mohs hardness is 7-7.5. It typically shows a vitreous luster. The streak is white. Common colors include yellow, yellow-brown, brown.

Where is tsilaisite found?+

Notable localities include Tsilaisina, Madagascar; San Piero in Campo, Elba, Italy; Antananarivo, Madagascar.

How much is tsilaisite worth?+

Typical asking prices fall in the range of $50-500 depending on crystal size and clarity. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like tsilaisite?+

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

What minerals are found with tsilaisite?+

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

What kind of rock does tsilaisite form in?+

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

What is tsilaisite used for?+

Tsilaisite is used in collector.

Find tsilaisite on the map

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