Pararobertsite is a rare phosphate mineral typically found as microcrystalline crusts or powdery aggregates in granite pegmatites. It is often visually indistinguishable from its polymorph, robertsite, and usually requires X-ray diffraction for definitive identification.

Hardness

3-4

Mohs

Luster

Dull

Streak

White

Transparency

Opaque

mineralrareRobertsite Group family

Pararobertsite

Hardness: 3-4
Luster: Dull
Streak: White
Transparency: Opaque

Is this pararobertsite?

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 pararobertsite with a known reference. Pararobertsite sits at Mohs 3-4 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Pararobertsite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Pararobertsite typically shows a dull luster.
4
Match the color range
Compare against the expected color range: white, pale yellow.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: microcrystalline aggregates, crusts, powdery.

Often confused with

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

How to tell apart: Streak differs — Pararobertsite leaves white, Mitridatite leaves yellowish-white.

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Often found alongside pararobertsite

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

All properties

Chemical formula: Ca₂Mn₃(PO₄)₃(OH)₃·3H₂O
Mohs hardness: 3-4
Density: 3.37 g/cm³
Colors: White Pale Yellow
Streak: White
Luster: Dull
Transparency: Opaque
Crystal system: Monoclinic
Crystal habit: Microcrystalline Aggregates, Crusts, Powdery
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Phosphate-rich Granite Pegmatites
Typical price: $50-300 per specimen

Where rockhounds find pararobertsite

Classic worldwide localities

Tip Top mine, Custer, South Dakota, USA
Mangualde, Portugal

Field-hunting tip

Look in phosphate-rich granite pegmatites country — that is the host setting where pararobertsite typically forms. If you start seeing robertsite, fairfieldite, triphylite in float, you are in the right ground. Field specimens usually show a microcrystalline aggregates, crusts, powdery habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify pararobertsite?+

Mohs hardness is 3-4. It typically shows a dull luster. The streak is white. Common colors include white, pale yellow.

Where is pararobertsite found?+

Notable localities include Tip Top mine, Custer, South Dakota, USA; Mangualde, Portugal.

How much is pararobertsite worth?+

Typical asking prices fall in the range of $50-300 per specimen. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like pararobertsite?+

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

What minerals are found with pararobertsite?+

Pararobertsite commonly co-occurs with Robertsite, Fairfieldite, Triphylite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does pararobertsite form in?+

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

What is pararobertsite used for?+

Pararobertsite is used in collector.

Find pararobertsite on the map

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