Holdenite is a rare arsenate mineral most famously found in the Franklin and Sterling Hill mining districts. It is highly prized by collectors for its vibrant red-to-pink coloration and its brilliant yellow fluorescence under shortwave ultraviolet light.
Is this holdenite?
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 holdenite with a known reference. Holdenite 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. Holdenite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Holdenite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: red, pink, orange-red.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: tabular crystals, massive, granular.
Often confused with
Holdenite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Holdenite leaves white, Sphalerite leaves white to yellow-brown; luster reads vitreous on Holdenite and resinous to submetallic on Sphalerite.
How to tell apart: Willemite is the harder of the two (Mohs 5.5 vs. 3-4).
How to tell apart: Streak differs, so Holdenite leaves white, Zincite leaves orange-yellow; luster reads vitreous on Holdenite and sub-adamantine on Zincite.
Often found alongside holdenite
Minerals reported to co-occur with holdenite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Mn,Zn,Mg)₈(Zn,Mg)(AsO₄)₂(OH)₈
- Mohs hardness
- 3-4
- Density
- 4.15 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Orthorhombic
- Crystal habit
- Tabular Crystals, Massive, Granular
- Cleavage
- Poor On {110}
- Fluorescence
- Bright Yellow Under SW UV
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Metamorphic Zinc Ore Bodies
- Typical price
- $50-500 thumbnail, $500-2000 cabinet specimen
Where rockhounds find holdenite
Classic worldwide localities
- Franklin, New Jersey, USA
- Sterling Hill, New Jersey, USA
Field-hunting tip
Look in hydrothermal metamorphic zinc ore bodies country, the host setting where holdenite typically forms. If you start seeing willemite, franklinite, zincite in float, you are in the right ground. Field specimens usually show a tabular crystals, massive, granular habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find holdenite on the map
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