Brumadoite is a rare copper selenite mineral found primarily in the magnesite mines of Bahia, Brazil. It typically appears as small, bright yellow to greenish-yellow tabular crystals or radiating sprays within vugs and fractures. Collectors prize it for its unique chemistry and association with rare selenium-bearing species.

Hardness

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrare

Brumadoite

Hardness: 3
Luster: Vitreous
Streak: White
Transparency: Transparent

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Is this brumadoite?

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

Often confused with

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

mineral

Chalcomenite

Mohs 2.5

How to tell apart: Streak differs — Brumadoite leaves white, Chalcomenite leaves pale blue.

How to tell apart: Streak differs — Brumadoite leaves white, Malachite leaves light green.

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Often found alongside brumadoite

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

All properties

Chemical formula: Cu₃(SeO₃)₂(OH)₄
Mohs hardness: 3
Density: 4.8 g/cm³
Colors: Yellow Greenish-yellow
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Monoclinic
Crystal habit: Tabular Crystals, Radiating Aggregates
Cleavage: Good
Rarity: Rare
Uses: Collector
Host rock: Hydrothermal Veins in Magnesite Deposits
Typical price: $50-500 depending on specimen size and clarity

Where rockhounds find brumadoite

Classic worldwide localities

Brumado, Bahia, Brazil

Field-hunting tip

Look in hydrothermal veins in magnesite deposits country — that is the host setting where brumadoite typically forms. If you start seeing chalcomenite, magnesite, dolomite in float, you are in the right ground. Field specimens usually show a tabular crystals, radiating aggregates habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify brumadoite?+

Mohs hardness is 3. It typically shows a vitreous luster. The streak is white. Common colors include yellow, greenish-yellow.

Where is brumadoite found?+

Notable localities include Brumado, Bahia, Brazil.

How much is brumadoite 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 brumadoite safe to handle?+

It contains toxic constituents. Contains copper and selenium; wash hands thoroughly after handling and avoid inhaling dust. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like brumadoite?+

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

What minerals are found with brumadoite?+

Brumadoite commonly co-occurs with Chalcomenite, Magnesite, Dolomite, Quartz. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does brumadoite form in?+

Brumadoite typically forms in hydrothermal veins in magnesite deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

What is brumadoite used for?+

Brumadoite is used in collector.

Find brumadoite on the map

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