Sterlinghillite is an extremely rare manganese arsenate mineral known primarily from the famous Sterling Hill Mine. It usually occurs as microscopic, white to colorless platy crystals or crusts that are best identified by their characteristic bright white fluorescence under short-wave UV light.

Hardness

Mohs

Luster

Pearly

Streak

White

Transparency

Translucent

mineralrare

Sterlinghillite

Hardness: 2
Luster: Pearly
Streak: White
Transparency: Translucent

Is this sterlinghillite?

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

Often confused with

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

mineral

Austinite

Mohs 4

How to tell apart: Austinite is the harder of the two (Mohs 4 vs. 2); luster reads pearly on Sterlinghillite and vitreous on Austinite.

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Often found alongside sterlinghillite

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

All properties

Chemical formula: Mn₃(AsO₄)₂(OH)₂·4H₂O
Mohs hardness: 2
Density: 3.5 g/cm³
Colors: White Colorless
Streak: White
Luster: Pearly
Transparency: Translucent
Crystal system: Monoclinic
Crystal habit: Platy Crystals, Crusts, Radial Aggregates
Cleavage: Perfect in One Direction
Fluorescence: Bright White Under SW UV
Rarity: Rare
Uses: Collector
Host rock: Hydrothermal Veins in Metamorphosed Zinc-manganese Ore Bodies
Typical price: $50-500 thumbnail depending on matrix and fluorescence quality

Where rockhounds find sterlinghillite

Classic worldwide localities

Sterling Hill Mine, New Jersey, USA

Field-hunting tip

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

Common questions

How do you identify sterlinghillite?+

Mohs hardness is 2. It typically shows a pearly luster. The streak is white. Common colors include white, colorless.

Where is sterlinghillite found?+

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

How much is sterlinghillite worth?+

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

Is sterlinghillite safe to handle?+

It contains toxic constituents. Contains arsenic, a toxic element. Handle with care, avoid creating dust, and wash hands thoroughly after handling. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like sterlinghillite?+

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

What minerals are found with sterlinghillite?+

Sterlinghillite commonly co-occurs with willemite, franklinite, zincite, jarosewichite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does sterlinghillite form in?+

Sterlinghillite typically forms in hydrothermal veins in metamorphosed zinc-manganese ore bodies. Working float back to the host body is the standard way to chase a fresh occurrence.

What is sterlinghillite used for?+

Sterlinghillite is used in collector.

Find sterlinghillite on the map

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