Minehillite is a rare phyllosilicate mineral uniquely associated with the zinc deposits of the Franklin Mining District. It is most easily identified by its bright blue fluorescence under ultraviolet light and its characteristic micaceous, platy crystal structure.

Hardness

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrarePhyllosilicate family

Minehillite

Hardness: 3
Luster: Vitreous
Streak: White
Transparency: Transparent

Is this minehillite?

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 minehillite with a known reference. Minehillite sits at Mohs 3 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Minehillite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Minehillite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: white, colorless, pale yellow.
5
Look at form & habit
Crystal system: hexagonal. Typical habit: platy crystals, micaceous aggregates.

Often confused with

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

mineral

Clinohedrite

Mohs 5

How to tell apart: Clinohedrite is the harder of the two (Mohs 5 vs. 3).

Compare →

Often found alongside minehillite

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

All properties

Chemical formula: (K,Na,Pb)₁₀(Zn,Mg,Fe,Mn)₈(Si,Be)₁₂O₃₀(OH,F)₄
Mohs hardness: 3
Density: 2.83 g/cm³
Colors: White Colorless Pale Yellow
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Hexagonal
Crystal habit: Platy Crystals, Micaceous Aggregates
Cleavage: Perfect Basal
Fluorescence: Bright Blue Under UV
Rarity: Rare
Uses: Collector, Scientific Research
Host rock: Metamorphosed Zinc Ore Bodies
Typical price: $50-500 depending on specimen size and clarity

Where rockhounds find minehillite

Classic worldwide localities

Franklin Mine, New Jersey, USA
Sterling Hill Mine, New Jersey, USA

Field-hunting tip

Look in metamorphosed zinc ore bodies country — that is the host setting where minehillite typically forms. If you start seeing willemite, franklinite, zincite in float, you are in the right ground. Field specimens usually show a platy crystals, micaceous aggregates habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify minehillite?+

Mohs hardness is 3. It typically shows a vitreous luster. The streak is white. Common colors include white, colorless, pale yellow.

Where is minehillite found?+

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

How much is minehillite worth?+

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

Is minehillite safe to handle?+

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

What rocks look like minehillite?+

Minehillite is most often confused with Clinohedrite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with minehillite?+

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

What kind of rock does minehillite form in?+

Minehillite typically forms in metamorphosed zinc ore bodies. Working float back to the host body is the standard way to chase a fresh occurrence.

What is minehillite used for?+

Minehillite is used in collector, scientific research.

Find minehillite on the map

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