Bostwickite is a rare manganese silicate mineral primarily found in the ore bodies of the Franklin Mining District in New Jersey. It is highly valued by collectors for its striking bright orange fluorescence under short-wave ultraviolet light and its distinctive fibrous, acicular crystal habit.
Is this bostwickite?
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 bostwickite with a known reference. Bostwickite sits at Mohs 2.5-3 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Bostwickite leaves a yellowish-brown streak.
- 3Read the lusterHold the specimen under a strong light. Bostwickite typically shows a silky luster.
- 4Match the color rangeCompare against the expected color range: dark brown, reddish-brown.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: acicular crystals.
Often confused with
Bostwickite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside bostwickite
Minerals reported to co-occur with bostwickite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ca₃Mn₆Si₃O₁₈(OH)₆·2H₂O
- Mohs hardness
- 2.5-3
- Density
- 2.9 g/cm³
- Colors
- Streak
- Yellowish-brown
- Luster
- Silky
- Transparency
- Opaque
- Crystal system
- Orthorhombic
- Crystal habit
- Acicular Crystals
- Cleavage
- None
- Fluorescence
- Bright Orange Under SW UV
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Veins in Metamorphosed Zinc Ore Deposits
- Typical price
- $50-500 thumbnail
Where rockhounds find bostwickite
Classic worldwide localities
- Franklin Mine, New Jersey, USA
- Sterling Hill Mine, New Jersey, USA
Field-hunting tip
Look in hydrothermal veins in metamorphosed zinc ore deposits country — that is the host setting where bostwickite typically forms. If you start seeing willemite, franklinite, zincite in float, you are in the right ground. Field specimens usually show a acicular crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find bostwickite on the map
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