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 pale orange streak.
- 3Read the lusterHold the specimen under a strong light. Ogdensburgite typically shows a resinous 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.
How to tell apart: Streak differs, so Ogdensburgite leaves pale orange, Veszelyite leaves light green; luster reads resinous on Ogdensburgite and vitreous on Veszelyite.
How to tell apart: Streak differs, so Ogdensburgite leaves pale orange, Austinite leaves white; luster reads resinous on Ogdensburgite and subadamantine to silky on Austinite.
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
- 3.11 g/cm³
- Streak
- Pale Orange
- Luster
- Resinous
- Transparency
- Translucent
- Crystal system
- Orthorhombic
- Crystal habit
- Acicular or Lath-like Crystals in Radiating Clusters
- Cleavage
- On {001}, Perfect; On {010}, {100}, Poor
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Zinc Ore Bodies in Metamorphosed Limestone
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, 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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