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. Falgarite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Falgarite typically shows a vitreous luster.
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 5.5-6.5 vs. 2-3).

Compare →

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

Look in sedimentary deposits country, the host setting where falgarite typically forms. If you start seeing sand, soil components in float, you are in the right ground. Field specimens usually show a isometric or pseudo-octahedral individual crystals habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify falgarite?+

Mohs hardness is 2-3. It typically shows a vitreous luster. 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.

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?+

Falgarite typically forms in 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.