Rumseyite is a very rare lead oxyhalide mineral first discovered in the Big Bunch mine in Arizona. It typically occurs as tiny, tabular, pale orange-brown crystals within oxidized lead-bearing veins and is highly prized by micromount collectors.
Is this rumseyite?
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 rumseyite with a known reference. Rumseyite sits at Mohs ~3, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: pale orange-brown.
- 5Look at form & habitCrystal system: tetragonal. Typical habit: tabular crystals.
Often confused with
Rumseyite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside rumseyite
Minerals reported to co-occur with rumseyite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Pb₂OFCl
- Mohs hardness
- ~3
- Density
- 7.72 g/cm³
- Colors
- Pale orange-brown
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Tetragonal
- Crystal habit
- Tabular crystals
- Cleavage
- Perfect on {100}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Part of an assemblage of lead oxychloride minerals that occur in cavities in manganese oxide pods in limestone
Where rockhounds find rumseyite
Classic worldwide localities
- Torr Works (Merehead) quarry, near the village of Cranmore, Somerset, England
Field-hunting tip
Where it forms: Part of an assemblage of lead oxychloride minerals that occur in cavities in manganese oxide pods in limestone. If you start seeing calcite, cerussite, diaboleite in float, you are in the right ground. Typical habit: tabular crystals. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify rumseyite?+
Where is rumseyite found?+
Is rumseyite safe to handle?+
What rocks look like rumseyite?+
What minerals are found with rumseyite?+
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Find rumseyite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
