Ogdensburgite is a rare secondary arsenic-bearing mineral discovered at the famous Franklin-Sterling Hill mining district. It typically appears as delicate, bright yellow acicular or lath-like crystals forming small sprays or crusts on ore specimens.
Is this ogdensburgite?
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 ogdensburgite with a known reference. Ogdensburgite sits at Mohs 3-4 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Ogdensburgite leaves a yellow streak.
- 3Read the lusterHold the specimen under a strong light. Ogdensburgite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: yellow, yellowish-orange, brownish-yellow.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: acicular or lath-like crystals in radiating clusters.
Often confused with
Ogdensburgite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside ogdensburgite
Minerals reported to co-occur with ogdensburgite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ca₂Fe₃³⁺(AsO₄)₃(OH)₃·5H₂O
- Mohs hardness
- 3-4
- Density
- 3.55 g/cm³
- Streak
- Yellow
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Orthorhombic
- Crystal habit
- Acicular or Lath-like Crystals in Radiating Clusters
- Cleavage
- None Observed
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Zinc Ore Bodies in Metamorphosed Limestone
- Typical price
- $50-300 per specimen depending on size and quality
Where rockhounds find ogdensburgite
Classic worldwide localities
- Sterling Hill Mine, New Jersey, USA
Field-hunting tip
Look in zinc ore bodies in metamorphosed limestone country — that is the host setting where ogdensburgite typically forms. If you start seeing willemite, franklinite, zincite in float, you are in the right ground. Field specimens usually show a acicular or lath-like crystals in radiating clusters habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find ogdensburgite on the map
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