Falgarite is a rare potassium vanadium sulfate that forms turquoise isometric or pseudo-octahedral individual crystals. It is a fumarolic, formed directly from gas emitted by a natural underground coal fire. It was first described from Kuhi-Malik gorge near Ravat kishlak, Fan-Yagnob coal deposit, ~100 km north of Dushanbe, Tajikistan.

Hardness

2-3

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrare

Falgarite

Hardness: 2-3
Luster: Vitreous
Streak: White
Transparency: Transparent

No image

Is this falgarite?

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 falgarite with a known reference. Falgarite sits at Mohs 2-3, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: white.
3
Read the luster
Hold the specimen under a strong light. Luster: vitreous.
4
Match the color range
Compare against the expected color range: turquoise, green.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: isometric or pseudo-octahedral individual crystals.

Often confused with

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

mineral

Fulgurite

Mohs 6.5-7

How to tell apart: Fulgurite is the harder of the two (Mohs 6.5-7 vs. 2-3); luster reads vitreous on Falgarite and glassy on Fulgurite.

How to tell apart: Lechatelierite is the harder of the two (Mohs 6.5 vs. 2-3).

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All properties

Chemical formula: K₄(VO)₃(SO₄)₅
Mohs hardness: 2-3
Density: 2.87 g/cm³
Colors: Turquoise Green
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Monoclinic
Crystal habit: Isometric or pseudo-octahedral individual crystals
Cleavage: None
Rarity: Rare
Uses: Collector, Scientific research
Host rock: sedimentary deposits

Where rockhounds find falgarite

Classic worldwide localities

Kuhi-Malik gorge near Ravat kishlak, Fan-Yagnob coal deposit, Tajikistan

Field-hunting tip

Where it forms: sedimentary deposits. If you start seeing sand, soil components in float, you are in the right ground. Typical habit: isometric or pseudo-octahedral individual crystals. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify falgarite?+

Mohs hardness is 2-3. Luster: vitreous. The streak is white. Common colors include turquoise, green.

Where is falgarite found?+

Notable localities include Kuhi-Malik gorge near Ravat kishlak, Fan-Yagnob coal deposit, Tajikistan.

Is falgarite safe to handle?+

Falgarite contains vanadium. Wash your hands afterwards, never grind or breathe the dust, and store it apart from specimens you handle often.

What rocks look like falgarite?+

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

What minerals are found with falgarite?+

Falgarite commonly co-occurs with sand, soil components. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does falgarite form in?+

Where it forms: sedimentary deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

What is falgarite used for?+

Falgarite is used in collector, scientific research.

Find falgarite on the map

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