Jonassonite is a rare bismuth-gold sulfide mineral typically found as small grains within hydrothermal gold deposits. It is often identified via microprobe analysis due to its visual similarity to other metallic sulfide minerals found in association with gold.

Hardness

2.5

Mohs

Luster

Metallic

Streak

Black

Transparency

Opaque

mineralrare

Jonassonite

Hardness: 2.5
Luster: Metallic
Streak: Black
Transparency: Opaque

No image

Is this jonassonite?

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 jonassonite with a known reference. Jonassonite 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. Jonassonite leaves a black streak.
3
Read the luster
Hold the specimen under a strong light. Jonassonite typically shows a metallic luster.
4
Match the color range
Compare against the expected color range: lead-gray, silver-white.
5
Look at form & habit
Crystal system: hexagonal. Typical habit: anhedral grains.

Often confused with

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

mineral

Bismuthinite

Mohs 2

How to tell apart: Streak differs — Jonassonite leaves black, Bismuthinite leaves lead-gray.

How to tell apart: Streak differs — Jonassonite leaves black, Tetradymite leaves lead-gray.

Compare →

Often found alongside jonassonite

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

All properties

Chemical formula: AuBi₅S₄
Mohs hardness: 2.5
Density: 9.79 g/cm³
Colors: Lead-gray Silver-white
Streak: Black
Luster: Metallic
Transparency: Opaque
Crystal system: Hexagonal
Crystal habit: Anhedral Grains
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Hydrothermal Gold Deposits
Typical price: $50-500 depending on specimen size and purity

Where rockhounds find jonassonite

Classic worldwide localities

Jonas Mine, Brazil
various gold-telluride deposits

Field-hunting tip

Look in hydrothermal gold deposits country — that is the host setting where jonassonite typically forms. If you start seeing native gold, bismuthinite, tetradymite in float, you are in the right ground. Field specimens usually show a anhedral grains habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify jonassonite?+

Mohs hardness is 2.5. It typically shows a metallic luster. The streak is black. Common colors include lead-gray, silver-white.

Where is jonassonite found?+

Notable localities include Jonas Mine, Brazil; various gold-telluride deposits.

How much is jonassonite worth?+

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

Is jonassonite safe to handle?+

It contains toxic constituents. Contains bismuth, sulfur, and gold; as with most heavy metal-bearing sulfide minerals, avoid inhaling dust or ingesting particles and wash hands thoroughly after handling. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like jonassonite?+

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

What minerals are found with jonassonite?+

Jonassonite commonly co-occurs with native gold, bismuthinite, tetradymite, pyrite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does jonassonite form in?+

Jonassonite typically forms in hydrothermal gold deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

What is jonassonite used for?+

Jonassonite is used in collector.

Find jonassonite on the map

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