Argesite is a rare ammonium sulfate mineral primarily found in volcanic fumarolic environments. It typically occurs as small, delicate, colorless to white crystals that are highly soluble in water and sensitive to humidity.

Hardness

2.5

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrare

Argesite

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

No image

Is this argesite?

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 argesite with a known reference. Argesite 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. Argesite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Argesite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: white, colorless.
5
Look at form & habit
Crystal system: orthorhombic. Typical habit: tabular crystals, crusts.

Often confused with

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

Often found alongside argesite

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

All properties

Chemical formula: (NH₄)₂SO₄
Mohs hardness: 2.5
Density: 2.44 g/cm³
Colors: White Colorless
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Orthorhombic
Crystal habit: Tabular Crystals, Crusts
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Volcanic Fumaroles
Typical price: $20-100 per specimen

Where rockhounds find argesite

Classic worldwide localities

Mount Arges, Romania
fumaroles of volcanoes

Field-hunting tip

Look in volcanic fumaroles country — that is the host setting where argesite typically forms. If you start seeing mascagnite, sal ammoniac, sulfur in float, you are in the right ground. Field specimens usually show a tabular crystals, crusts habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify argesite?+

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

Where is argesite found?+

Notable localities include Mount Arges, Romania; fumaroles of volcanoes.

How much is argesite worth?+

Typical asking prices fall in the range of $20-100 per specimen. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like argesite?+

Argesite is most often confused with Mascagnite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with argesite?+

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

What kind of rock does argesite form in?+

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

What is argesite used for?+

Argesite is used in collector.

Find argesite on the map

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