Matildite is a silver bismuth sulfide mineral frequently found in complex intergrowths with galena, often formed through the exsolution of silver-rich galena as it cools. Collectors typically find it as massive, metallic-gray blebs within sulfide ore deposits. It is best identified by its high density and metallic luster, often requiring microscopic examination to distinguish from associated sulfide species.

Hardness

2.5-3

Mohs

Luster

Metallic

Streak

Black

Transparency

Opaque

mineraluncommon

Matildite

Hardness: 2.5-3
Luster: Metallic
Streak: Black
Transparency: Opaque

Is this matildite?

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 matildite with a known reference. Matildite sits at Mohs 2.5-3, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Matildite leaves a black streak.
3
Read the luster
Hold the specimen under a strong light. Matildite typically shows a metallic luster.
4
Match the color range
Compare against the expected color range: lead-gray, black.
5
Look at form & habit
Crystal system: trigonal. Typical habit: rarely as distinct crystals, usually massive or as intimate intergrowths with galena.

Often confused with

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

mineral

Galena

Mohs 2.5

How to tell apart: Streak differs, so Matildite leaves black, Galena leaves lead-gray.

How to tell apart: Streak differs, so Matildite leaves black, Bismuthinite leaves lead-gray.

Often found alongside matildite

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

All properties

Chemical formula: AgBiS₂
Mohs hardness: 2.5-3
Density: 6.4-6.5 g/cm³
Colors: Lead-gray Black
Streak: Black
Luster: Metallic
Transparency: Opaque
Crystal system: Trigonal
Crystal habit: Rarely as Distinct Crystals, Usually Massive or as Intimate Intergrowths with Galena
Cleavage: None
Rarity: Uncommon
Uses: Collector, Scientific Study
Host rock: Hydrothermal Veins
Typical price: $20-150 for small specimens

Where rockhounds find matildite

Classic worldwide localities

Matildite locality, Peru
Japan
Germany
USA
Bolivia

Field-hunting tip

Look in hydrothermal veins country, the host setting where matildite typically forms. If you start seeing galena, bismuthinite, chalcopyrite in float, you are in the right ground. Field specimens usually show a rarely as distinct crystals, usually massive or as intimate intergrowths with galena habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify matildite?+

Mohs hardness is 2.5-3. It typically shows a metallic luster. The streak is black. Common colors include lead-gray, black.

Where is matildite found?+

Notable localities include Matildite locality, Peru; Japan; Germany; USA; Bolivia.

How much is matildite worth?+

Typical asking prices fall in the range of $20-150 for small specimens. Quality, size, and provenance can move individual specimens well outside that range.

Is matildite safe to handle?+

It contains toxic constituents. Contains silver, bismuth, and sulfur; handle with care and avoid inhalation of dust or ingestion. Wash hands thoroughly after handling. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like matildite?+

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

What minerals are found with matildite?+

Matildite commonly co-occurs with Galena, Bismuthinite, Chalcopyrite, Siderite, Pyrite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does matildite form in?+

Matildite typically forms in hydrothermal veins. Working float back to the host body is the standard way to chase a fresh occurrence.

What is matildite used for?+

Matildite is used in collector, scientific study.

Find matildite on the map

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