Segnitite is a rare lead-iron arsenate mineral primarily found in the oxidized zones of lead-rich hydrothermal mineral deposits. Collectors typically search for its distinct yellow to brownish-orange rhombohedral crystals, which often form in the same cavities as wulfenite and cerussite.
Is this segnitite?
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 segnitite with a known reference. Segnitite 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: pale yellow.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous to adamantine.
- 4Match the color rangeCompare against the expected color range: greenish brown, yellow brown.
- 5Look at form & habitCrystal system: trigonal. Typical habit: rhombohedral crystals, sometimes forming crusts or pseudo-cubic aggregates.
Often confused with
Segnitite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Segnitite leaves pale yellow, Beudantite leaves grayish yellow to green.
How to tell apart: Luster reads vitreous to adamantine on Segnitite and dull to vitreous on fractures on Duftite.
How to tell apart: Streak differs, so Segnitite leaves pale yellow, Mimetite leaves white; luster reads vitreous to adamantine on Segnitite and resinous to subadamantine on Mimetite.
Often found alongside segnitite
Minerals reported to co-occur with segnitite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- PbFe₃(AsO₄)(AsO₃OH)(OH)₆
- Mohs hardness
- ~4
- Density
- 4.77 g/cm³
- Streak
- Pale yellow
- Luster
- Vitreous to adamantine
- Transparency
- Transparent to translucent
- Crystal system
- Trigonal
- Crystal habit
- Rhombohedral crystals, sometimes forming crusts or pseudo-cubic aggregates
- Cleavage
- On {0001}, good
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Of rare occurrence in the oxidized zone of a Pb–Zn orebody (Broken Hill, Australia); in a dolostone-hosted hydrothermal polymetallic ore deposit (Tsumeb, Namibia)
Where rockhounds find segnitite
Classic worldwide localities
- Centennial Eureka mine, Tintic district, Juab Co., Utah, USA
- Broken Hill, New South Wales, and at Coppin Pool, about 41 km east-southeast of Mt. Tom Price, Western Australia
- Tsumeb, Namibia
- Penberthy Croft mine, St. Hilary, Cornwall, England
Field-hunting tip
Where it forms: Of rare occurrence in the oxidized zone of a Pb–Zn orebody (Broken Hill, Australia); in a dolostone-hosted hydrothermal polymetallic ore deposit (Tsumeb, Namibia). If you start seeing beudantite–corkite, adamite–olivenite, duftite in float, you are in the right ground. Typical habit: rhombohedral crystals, sometimes forming crusts or pseudo-cubic aggregates. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify segnitite?+
Where is segnitite found?+
Is segnitite safe to handle?+
What rocks look like segnitite?+
What minerals are found with segnitite?+
What kind of rock does segnitite form in?+
What is segnitite used for?+
Find segnitite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
