Brumadoite is a rare copper tellurium hydroxide, typically blue. It is a late fracture-filling mineral in coarse-grained magnesite. Associated minerals include magnesite, mottramite and quartz. It was first described from Pedra Preta mine, Serra das Éguas, Brumado, Bahia, Brazil.

Hardness

Mohs

Luster

Vitreous

Streak

Pale Blue

Transparency

Transparent

mineralrare

Brumadoite

Hardness: 3
Luster: Vitreous
Streak: Pale Blue
Transparency: Transparent

No image

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 pale blue 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: blue.
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.

How to tell apart: Streak differs, so Brumadoite leaves pale blue, Malachite leaves light green.

Compare →

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(Te⁶⁺O₄)(OH)₄·5H₂O
Mohs hardness: 3
Density: 2.60 g/cm³
Colors: Blue
Streak: Pale Blue
Luster: Vitreous
Transparency: Transparent
Crystal system: Monoclinic
Crystal habit: Tabular Crystals, Radiating Aggregates
Cleavage: None Observed
Rarity: Rare
Uses: Collector
Host rock: Hydrothermal Veins in Magnesite Deposits

Where rockhounds find brumadoite

Classic worldwide localities

Brumado, Bahia, Brazil

Field-hunting tip

Look in hydrothermal veins in magnesite deposits country, 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 pale blue. Common colors include blue.

Where is brumadoite found?+

Notable localities include Brumado, Bahia, Brazil.

Is brumadoite safe to handle?+

It contains toxic constituents. Contains copper and tellurium, which are 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 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.