Hancockite is a rare lead-bearing member of the epidote group typically found in the famous zinc-manganese orebodies of Franklin and Sterling Hill. Collectors look for its distinctive deep reddish-brown tabular crystals that often display a subtle, vitreous luster.
Is this hancockite?
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 hancockite with a known reference. Hancockite sits at Mohs 6-7, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Hancockite leaves a light brown streak.
- 3Read the lusterHold the specimen under a strong light. Hancockite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: reddish-brown, brown, black.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic to tabular crystals.
Often confused with
Hancockite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Hancockite leaves light brown, Epidote leaves white.
How to tell apart: Streak differs, so Hancockite leaves light brown, Allanite leaves gray; luster reads vitreous on Hancockite and submetallic on Allanite.
How to tell apart: Streak differs, so Hancockite leaves light brown, Clinozoisite leaves white.
Often found alongside hancockite
Minerals reported to co-occur with hancockite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Pb,Ca,Sr)₂ (Al,Fe,Mn)₃ (Si₂O₇)(SiO₄)O(OH)
- Mohs hardness
- 6-7
- Density
- 4.05 g/cm³
- Colors
- Streak
- Light Brown
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic to Tabular Crystals
- Cleavage
- Distinct On One Face
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Metamorphosed Zinc Ore Deposits
- Typical price
- $50-500 depending on crystal size and quality
Where rockhounds find hancockite
Classic worldwide localities
- Franklin, New Jersey, USA
- Sterling Hill, New Jersey, USA
Field-hunting tip
Look in metamorphosed zinc ore deposits country, the host setting where hancockite typically forms. If you start seeing willemite, franklinite, andradite in float, you are in the right ground. Field specimens usually show a prismatic to tabular crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find hancockite on the map
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