Jeankempite is a rare calcium arsenate, typically colorless to white. It occurs in intergrowths with guérinite coating oxidized copper arsenides. Associated minerals include calcite, ankerite and rauenthalite. It was first described from the Mohawk No. 2 mine, Mohawk, Keweenaw Co., Michigan, USA.

Hardness

2-3

Mohs

Luster

Waxy

Streak

White

Transparency

Transparent

mineralrare

Jeankempite

Hardness: 2-3
Luster: Waxy
Streak: White
Transparency: Transparent

No image

Is this jeankempite?

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

Often confused with

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

mineral

Stewartite

Mohs 1.5-2

How to tell apart: Luster reads waxy on Jeankempite and vitreous on Stewartite.

How to tell apart: Luster reads waxy on Jeankempite and vitreous on Laueite.

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Often found alongside jeankempite

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

All properties

Chemical formula: Ca₅(AsO₄)₂(AsO₃OH)₂(H₂O)₇
Mohs hardness: 2-3
Density: 2.92 g/cm³
Colors: Colorless White
Streak: White
Luster: Waxy
Transparency: Transparent
Crystal system: Triclinic
Crystal habit: Acicular Crystals
Cleavage: Perfect
Rarity: Rare
Uses: Collector
Host rock: Phosphate-rich Pegmatites

Where rockhounds find jeankempite

Classic worldwide localities

Jeankemp mine, South Africa

Field-hunting tip

Look in phosphate-rich pegmatites country, the host setting where jeankempite typically forms. If you start seeing triplite, phosphosiderite, ludlamite in float, you are in the right ground. Field specimens usually show a acicular crystals habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify jeankempite?+

Mohs hardness is 2-3. It typically shows a waxy luster. The streak is white. Common colors include colorless, white.

Where is jeankempite found?+

Notable localities include Jeankemp mine, South Africa.

Is jeankempite safe to handle?+

It contains toxic constituents. Contains arsenic, which is toxic if ingested or inhaled as dust. Wash hands thoroughly after handling and avoid creating dust. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like jeankempite?+

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

What minerals are found with jeankempite?+

Jeankempite commonly co-occurs with Triplite, Phosphosiderite, Ludlamite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does jeankempite form in?+

Jeankempite typically forms in phosphate-rich pegmatites. Working float back to the host body is the standard way to chase a fresh occurrence.

What is jeankempite used for?+

Jeankempite is used in collector.

Find jeankempite on the map

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