Lumsdenite is a rare silver-gold-antimony sulfide mineral typically found in low-temperature hydrothermal vein deposits. It is often identified by its metallic luster and association with other precious metal sulfides, requiring analytical methods for positive field identification.

Hardness

3.5

Mohs

Luster

Metallic

Streak

Black

Transparency

Opaque

mineralrareStannite Group family

Lumsdenite

Hardness: 3.5
Luster: Metallic
Streak: Black
Transparency: Opaque

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Is this lumsdenite?

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 lumsdenite with a known reference. Lumsdenite sits at Mohs 3.5, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Lumsdenite leaves a black streak.
3
Read the luster
Hold the specimen under a strong light. Lumsdenite typically shows a metallic luster.
4
Match the color range
Compare against the expected color range: gray, steel gray.
5
Look at form & habit
Crystal system: tetragonal. Typical habit: massive, granular.

Often confused with

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

Often found alongside lumsdenite

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

All properties

Chemical formula: Ag₃AuSb₂S₃
Mohs hardness: 3.5
Density: 4.45 g/cm³
Colors: Gray Steel Gray
Streak: Black
Luster: Metallic
Transparency: Opaque
Crystal system: Tetragonal
Crystal habit: Massive, Granular
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Hydrothermal Veins
Typical price: $50-300 per specimen

Where rockhounds find lumsdenite

Classic worldwide localities

Lumsden Mine, Canada
various epithermal vein deposits

Field-hunting tip

Look in hydrothermal veins country, the host setting where lumsdenite typically forms. If you start seeing quartz, pyrite, chalcopyrite in float, you are in the right ground. Field specimens usually show a massive, granular habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify lumsdenite?+

Mohs hardness is 3.5. It typically shows a metallic luster. The streak is black. Common colors include gray, steel gray.

Where is lumsdenite found?+

Notable localities include Lumsden Mine, Canada; various epithermal vein deposits.

How much is lumsdenite 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 lumsdenite safe to handle?+

It contains toxic constituents. Contains arsenic, antimony, and silver. Handle with care, avoid creating dust, and wash hands thoroughly after contact. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like lumsdenite?+

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

What minerals are found with lumsdenite?+

Lumsdenite commonly co-occurs with Quartz, Pyrite, Chalcopyrite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does lumsdenite form in?+

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

What is lumsdenite used for?+

Lumsdenite is used in collector.

Find lumsdenite on the map

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