Kolicite is an extremely rare manganese zinc silicate-arsenate mineral known almost exclusively from the Franklin-Sterling Hill mining district. It is prized by fluorescent mineral collectors for its vivid orange-red reaction under shortwave ultraviolet light.

Hardness

5-6

Mohs

Luster

Vitreous

Streak

Yellowish-orange

Transparency

Translucent

mineralrare

Kolicite

Hardness: 5-6
Luster: Vitreous
Streak: Yellowish-orange
Transparency: Translucent

Is this kolicite?

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 kolicite with a known reference. Kolicite sits at Mohs 5-6 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Kolicite leaves a yellowish-orange streak.
3
Read the luster
Hold the specimen under a strong light. Kolicite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: orange, reddish-orange.
5
Look at form & habit
Crystal system: orthorhombic. Typical habit: anhedral grains, massive.

Often confused with

Kolicite vs. its common look-alikes — and how to tell them apart in the field.

mineral

Willemite

Mohs 5.5

How to tell apart: Streak differs — Kolicite leaves yellowish-orange, Willemite leaves white.

How to tell apart: Streak differs — Kolicite leaves yellowish-orange, Hodgkinsonite leaves white.

Compare →

Often found alongside kolicite

Minerals reported to co-occur with kolicite. Spotting these in float or country rock is a strong cue you are in the right ground.

All properties

Chemical formula: Mn₇Zn₄As₂SiO₁₆(OH)₈
Mohs hardness: 5-6
Density: 3.84 g/cm³
Colors: Orange Reddish-orange
Streak: Yellowish-orange
Luster: Vitreous
Transparency: Translucent
Crystal system: Orthorhombic
Crystal habit: Anhedral Grains, Massive
Cleavage: Poor
Fluorescence: Bright Orange-red Under SW UV
Rarity: Rare
Uses: Collector
Host rock: Hydrothermal Zinc Deposits
Typical price: $50-500 thumbnail

Where rockhounds find kolicite

Classic worldwide localities

Sterling Hill Mine, New Jersey, USA

Field-hunting tip

Look in hydrothermal zinc deposits country — that is the host setting where kolicite typically forms. If you start seeing willemite, franklinite, zincite in float, you are in the right ground. Field specimens usually show a anhedral grains, massive habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify kolicite?+

Mohs hardness is 5-6. It typically shows a vitreous luster. The streak is yellowish-orange. Common colors include orange, reddish-orange.

Where is kolicite found?+

Notable localities include Sterling Hill Mine, New Jersey, USA.

How much is kolicite worth?+

Typical asking prices fall in the range of $50-500 thumbnail. Quality, size, and provenance can move individual specimens well outside that range.

Is kolicite safe to handle?+

It contains toxic constituents. Contains arsenic; handle with care and wash hands thoroughly after handling to avoid ingestion or inhalation of dust. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like kolicite?+

Kolicite is most often confused with Willemite, Hodgkinsonite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with kolicite?+

Kolicite commonly co-occurs with Willemite, Franklinite, Zincite, Hodgkinsonite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does kolicite form in?+

Kolicite typically forms in hydrothermal zinc deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

What is kolicite used for?+

Kolicite is used in collector.

Find kolicite on the map

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