Mummeite is a rare sulfosalt mineral primarily found as part of the lillianite homologous series. It typically presents as metallic lead-gray massive grains within hydrothermal ore deposits associated with other sulfide minerals.
Is this mummeite?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch mummeite with a known reference. Mummeite sits at Mohs 4, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: black.
- 3Read the lusterHold the specimen under a strong light. Luster: metallic.
- 4Match the color rangeCompare against the expected color range: silver gray.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: massive to fine-grained aggregates, rarely acicular crystals.
Often confused with
Mummeite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside mummeite
Minerals reported to co-occur with mummeite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Cu₀.₅₈Ag₃.₁₁Pb₁.₁₀Bi₆.₆₅S₁₃
- Mohs hardness
- 4
- Density
- 6.64 g/cm³
- Colors
- Streak
- Black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Monoclinic
- Crystal habit
- Massive to fine-grained aggregates, rarely acicular crystals
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In hydrothermal base-metal sulfide vein deposits
Where rockhounds find mummeite
Classic worldwide localities
- Alaska mine, Poughkeepsie Gulch, near Ouray (type locality) and at the Mike mine, Silverton district, San Juan Co., Colorado, USA
Field-hunting tip
Where it forms: In hydrothermal base-metal sulfide vein deposits. If you start seeing chalcopyrite, sphalerite, pyrite in float, you are in the right ground. Typical habit: massive to fine-grained aggregates, rarely acicular crystals. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify mummeite?+
Where is mummeite found?+
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What rocks look like mummeite?+
What minerals are found with mummeite?+
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Find mummeite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
