Pyroaurite is a member of the hydrotalcite group typically found as pearly, platy crystals or foliated masses in metamorphic environments. It is often distinguished by its characteristic waxy to pearly luster and soft, flexible flakes when found in thin, hexagonal plates.

Hardness

2.5

Mohs

Luster

Pearly

Streak

White

Transparency

Translucent

mineraluncommonHydrotalcite Group family

Pyroaurite

Hardness: 2.5
Luster: Pearly
Streak: White
Transparency: Translucent

Is this pyroaurite?

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 pyroaurite with a known reference. Pyroaurite sits at Mohs 2.5 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Pyroaurite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Pyroaurite typically shows a pearly luster.
4
Match the color range
Compare against the expected color range: yellow, brown, white, orange, colorless.
5
Look at form & habit
Crystal system: trigonal. Typical habit: platy crystals, foliated masses, or hexagonal plates.

Often confused with

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

Often found alongside pyroaurite

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

All properties

Chemical formula: Mg₆Fe₃⁺₂(OH)₁₆(CO₃)·4H₂O
Mohs hardness: 2.5
Density: 2.1-2.2 g/cm³
Colors: Yellow Brown White Orange Colorless
Streak: White
Luster: Pearly
Transparency: Translucent
Crystal system: Trigonal
Crystal habit: Platy Crystals, Foliated Masses, Or Hexagonal Plates
Cleavage: Perfect Basal
Rarity: Uncommon
Uses: Collector, Scientific Research
Host rock: Metamorphosed Limestones and Altered Mafic Rocks
Typical price: $10-60 for small specimens

Where rockhounds find pyroaurite

Classic worldwide localities

Långban, Sweden
Magnet Cove, USA
Khibiny Massif, Russia
Königsberg, Norway

Field-hunting tip

Look in metamorphosed limestones and altered mafic rocks country — that is the host setting where pyroaurite typically forms. If you start seeing brucite, calcite, aragonite in float, you are in the right ground. Field specimens usually show a platy crystals, foliated masses, or hexagonal plates habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify pyroaurite?+

Mohs hardness is 2.5. It typically shows a pearly luster. The streak is white. Common colors include yellow, brown, white, orange.

Where is pyroaurite found?+

Notable localities include Långban, Sweden; Magnet Cove, USA; Khibiny Massif, Russia; Königsberg, Norway.

How much is pyroaurite worth?+

Typical asking prices fall in the range of $10-60 for small specimens. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like pyroaurite?+

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

What minerals are found with pyroaurite?+

Pyroaurite commonly co-occurs with Brucite, Calcite, Aragonite, Serpentine, Magnetite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does pyroaurite form in?+

Pyroaurite typically forms in metamorphosed limestones and altered mafic rocks. Working float back to the host body is the standard way to chase a fresh occurrence.

What is pyroaurite used for?+

Pyroaurite is used in collector, scientific research.

Find pyroaurite on the map

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