Wallkilldellite is a rare arsenate mineral that occurs as distinct platy crystals or thin crusts, typically displaying a rich reddish color. It is primarily found in the complex manganese-zinc ore deposits of the Franklin-Sterling Hill district in New Jersey. Due to its rarity and specific chemical composition, it is highly sought after by advanced systematic mineral collectors.
Is this wallkilldellite?
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 wallkilldellite with a known reference. Wallkilldellite sits at Mohs 3.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Wallkilldellite leaves a yellowish-orange streak.
- 3Read the lusterHold the specimen under a strong light. Wallkilldellite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: red, brownish-red, orange-red.
- 5Look at form & habitCrystal system: trigonal. Typical habit: platy crystals, crusts.
Often confused with
Wallkilldellite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Wallkilldellite leaves yellowish-orange, Allactite leaves light brown.
How to tell apart: Flinkite is the harder of the two (Mohs 5 vs. 3.5); streak differs — Wallkilldellite leaves yellowish-orange, Flinkite leaves light brown.
Often found alongside wallkilldellite
Minerals reported to co-occur with wallkilldellite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ca₂Mn₃(AsO₄)₂(OH)₄·4H₂O
- Mohs hardness
- 3.5
- Density
- 2.8 g/cm³
- Streak
- Yellowish-orange
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Trigonal
- Crystal habit
- Platy Crystals, Crusts
- Cleavage
- Perfect
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Veins in Metamorphic Rocks
- Typical price
- $50-300 per specimen
Where rockhounds find wallkilldellite
Classic worldwide localities
- Sterling Hill Mine, New Jersey, USA
Field-hunting tip
Look in hydrothermal veins in metamorphic rocks country — that is the host setting where wallkilldellite typically forms. If you start seeing arsenates, calcite, willemite in float, you are in the right ground. Field specimens usually show a platy crystals, crusts habit, so train your eye for that shape before scanning the outcrop.
Common questions
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