Lafossaite is an extremely rare ammonium-lead chloride mineral first discovered in the fumarolic deposits of the La Fossa crater on Vulcano. It typically appears as small, cubic crystals associated with other sublimation products in geothermal volcanic environments.

Hardness

2.5

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrare

Lafossaite

Hardness: 2.5
Luster: Vitreous
Streak: White
Transparency: Transparent

Is this lafossaite?

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 lafossaite with a known reference. Lafossaite sits at Mohs 2.5 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Lafossaite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Lafossaite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: white, colorless, yellow.
5
Look at form & habit
Crystal system: cubic. Typical habit: subhedral to euhedral crystals.

Often confused with

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

Often found alongside lafossaite

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

All properties

Chemical formula: Pb(NH₄)Cl₃
Mohs hardness: 2.5
Density: 2.35 g/cm³
Colors: White Colorless Yellow
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Cubic
Crystal habit: Subhedral to Euhedral Crystals
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Volcanic Fumaroles
Typical price: $50-300 per specimen

Where rockhounds find lafossaite

Classic worldwide localities

La Fossa crater, Vulcano, Aeolian Islands, Italy

Field-hunting tip

Look in volcanic fumaroles country — that is the host setting where lafossaite typically forms. If you start seeing sal ammoniac, anglesite, galena in float, you are in the right ground. Field specimens usually show a subhedral to euhedral crystals habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify lafossaite?+

Mohs hardness is 2.5. It typically shows a vitreous luster. The streak is white. Common colors include white, colorless, yellow.

Where is lafossaite found?+

Notable localities include La Fossa crater, Vulcano, Aeolian Islands, Italy.

How much is lafossaite worth?+

Typical asking prices fall in the range of $50-300 per specimen. Quality, size, and provenance can move individual specimens well outside that range.

Is lafossaite safe to handle?+

It contains toxic constituents. Contains lead, which is toxic. Handle with care, avoid ingestion, inhalation of dust, or prolonged skin contact, and wash hands thoroughly after handling. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like lafossaite?+

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

What minerals are found with lafossaite?+

Lafossaite commonly co-occurs with Sal ammoniac, Anglesite, Galena, Sulfur. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does lafossaite form in?+

Lafossaite typically forms in volcanic fumaroles. Working float back to the host body is the standard way to chase a fresh occurrence.

What is lafossaite used for?+

Lafossaite is used in collector.

Find lafossaite on the map

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