Johnbaumite is an uncommon arsenate member of the apatite group named in honor of mineralogist John L. Baum. It typically occurs as small, pale prismatic crystals in metamorphic zinc deposits, most famously associated with the Franklin, New Jersey ore bodies.

Hardness

Mohs

Luster

Vitreous

Streak

White

Transparency

Translucent

mineralrareApatite Group family

Johnbaumite

Hardness: 5
Luster: Vitreous
Streak: White
Transparency: Translucent

Is this johnbaumite?

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

Often confused with

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

How to tell apart: Johnbaumite is noticeably harder (Mohs 5 vs. 3.5-4); luster reads vitreous on Johnbaumite and adamantine on Mimetite.

Compare →

Often found alongside johnbaumite

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

All properties

Chemical formula: Ca₅(AsO₄)₃OH
Mohs hardness: 5
Density: 3.55 g/cm³
Colors: White Colorless Pinkish-white Pale Yellow
Streak: White
Luster: Vitreous
Transparency: Translucent
Crystal system: Hexagonal
Crystal habit: Prismatic Crystals
Cleavage: Indistinct
Rarity: Rare
Uses: Collector
Host rock: Metamorphic Zinc Ore Deposits
Typical price: $50-500 depending on specimen size and clarity

Where rockhounds find johnbaumite

Classic worldwide localities

Franklin Mine, New Jersey, USA

Field-hunting tip

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

Common questions

How do you identify johnbaumite?+

Mohs hardness is 5. It typically shows a vitreous luster. The streak is white. Common colors include white, colorless, pinkish-white, pale yellow.

Where is johnbaumite found?+

Notable localities include Franklin Mine, New Jersey, USA.

How much is johnbaumite 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 johnbaumite safe to handle?+

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

What rocks look like johnbaumite?+

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

What minerals are found with johnbaumite?+

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

What kind of rock does johnbaumite form in?+

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

What is johnbaumite used for?+

Johnbaumite is used in collector.

Find johnbaumite on the map

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