Pyrochroite is a rare manganese hydroxide mineral that typically forms as soft, pearly, tabular crystals or foliated masses. Collectors should be aware that it is highly sensitive to air and will rapidly darken or turn black when exposed to oxygen due to oxidation into hausmannite. It is most famously found in the historic manganese mines of Långban and Franklin, usually occurring within metamorphosed ore bodies.

Hardness

2.5

Mohs

Luster

Pearly

Streak

White

Transparency

Translucent

mineraluncommon

Pyrochroite

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

Is this pyrochroite?

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 pyrochroite with a known reference. Pyrochroite 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. Pyrochroite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Pyrochroite typically shows a pearly luster.
4
Match the color range
Compare against the expected color range: yellow, brown, white.
5
Look at form & habit
Crystal system: trigonal. Typical habit: tabular crystals, foliated masses, platy.

Often confused with

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

Often found alongside pyrochroite

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

All properties

Chemical formula: Mn(OH)₂
Mohs hardness: 2.5
Density: 3.26 g/cm³
Colors: Yellow Brown White
Streak: White
Luster: Pearly
Transparency: Translucent
Crystal system: Trigonal
Crystal habit: Tabular Crystals, Foliated Masses, Platy
Cleavage: Perfect Basal
Rarity: Uncommon
Uses: Collector, Scientific Research
Host rock: Metamorphosed Manganese Ore Deposits
Typical price: $20-150 thumbnail to miniature specimen

Where rockhounds find pyrochroite

Classic worldwide localities

Långban, Sweden
Franklin, New Jersey, USA
Nordmark, Sweden
Jacupiranga, Brazil

Field-hunting tip

Look in metamorphosed manganese ore deposits country — that is the host setting where pyrochroite typically forms. If you start seeing hausmannite, manganosite, calcite in float, you are in the right ground. Field specimens usually show a tabular crystals, foliated masses, platy habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify pyrochroite?+

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

Where is pyrochroite found?+

Notable localities include Långban, Sweden; Franklin, New Jersey, USA; Nordmark, Sweden; Jacupiranga, Brazil.

How much is pyrochroite worth?+

Typical asking prices fall in the range of $20-150 thumbnail to miniature specimen. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like pyrochroite?+

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

What minerals are found with pyrochroite?+

Pyrochroite commonly co-occurs with Hausmannite, Manganosite, Calcite, Barite, Franklinite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does pyrochroite form in?+

Pyrochroite typically forms in metamorphosed manganese ore deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

What is pyrochroite used for?+

Pyrochroite is used in collector, scientific research.

Find pyrochroite on the map

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