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.

Hardness

6-7

Mohs

Luster

Vitreous

Streak

Grayish white

Transparency

Translucent

mineralrareEpidote Group family

Hancockite

Hardness: 6-7
Luster: Vitreous
Streak: Grayish white
Transparency: Translucent

Is this hancockite?

5-step field check

Run through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.

1
Test the hardness
Try to scratch hancockite with a known reference. Hancockite sits at Mohs 6-7, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: grayish white.
3
Read the luster
Hold the specimen under a strong light. Luster: vitreous.
4
Match the color range
Compare against the expected color range: crystals yellowish brown, yellow-green.
5
Look at form & habit
Crystal 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 grayish white, Allanite leaves gray; luster reads vitreous on Hancockite and submetallic on Allanite.

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: CaPbFeAl₂(Si₂O₇)(SiO₄)O(OH)
Mohs hardness: 6-7
Density: 4.03 g/cm³
Colors: Crystals yellowish brownYellow-green
Streak: Grayish white
Luster: Vitreous
Transparency: Translucent
Crystal system: Monoclinic
Crystal habit: Prismatic to tabular crystals
Cleavage: {001}, perfect
Rarity: Rare
Uses: Collector
Host rock: In a metamorphosed stratiform zinc deposit (Franklin, New Jersey, USA); in a metamorphosed manganese-iron orebody in skarns enclosed in dolomitic marble (Jakobsberg, Sweden)

Where rockhounds find hancockite

Classic worldwide localities

Franklin, Sussex Co., New Jersey, USA
Jakobsberg, Värmland, Sweden

Field-hunting tip

Where it forms: In a metamorphosed stratiform zinc deposit (Franklin, New Jersey, USA); in a metamorphosed manganese-iron orebody in skarns enclosed in dolomitic marble (Jakobsberg, Sweden). If you start seeing andradite, franklinite, manganaxinite in float, you are in the right ground. Typical habit: prismatic to tabular crystals. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify hancockite?+

Mohs hardness is 6-7. Luster: vitreous. The streak is grayish white. Common colors include crystals yellowish brown, yellow-green.

Where is hancockite found?+

Notable localities include Franklin, Sussex Co., New Jersey, USA; Jakobsberg, Värmland, Sweden.

Is hancockite safe to handle?+

Hancockite contains lead. Contains lead; wash hands after handling and avoid inhaling dust.

What rocks look like hancockite?+

Hancockite is most often confused with Epidote, Allanite, Clinozoisite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with hancockite?+

Hancockite commonly co-occurs with Andradite, Franklinite, Manganaxinite, Clinohedrite, Roeblingite, Datolite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does hancockite form in?+

Where it forms: In a metamorphosed stratiform zinc deposit (Franklin, New Jersey, USA); in a metamorphosed manganese-iron orebody in skarns enclosed in dolomitic marble (Jakobsberg, Sweden). Working float back to the host body is the standard way to chase a fresh occurrence.

What is hancockite used for?+

Hancockite is used in collector.

Find hancockite on the map

RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.