Carlosbarbosaite is a rare uranyl niobate mineral typically found as small, bright yellow acicular or prismatic crystals. It is primarily known from its type locality in Brazil, where it occurs within granitic pegmatites. Collectors should treat it with caution due to its uranium content.

Hardness

3-4

Mohs

Luster

Vitreous

Streak

Pale Yellow

Transparency

Translucent

mineralrare

Carlosbarbosaite

Hardness: 3-4
Luster: Vitreous
Streak: Pale Yellow
Transparency: Translucent

Is this carlosbarbosaite?

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 carlosbarbosaite with a known reference. Carlosbarbosaite 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. Carlosbarbosaite leaves a pale yellow streak.
3
Read the luster
Hold the specimen under a strong light. Carlosbarbosaite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: yellow, yellowish-orange.
5
Look at form & habit
Crystal system: orthorhombic. Typical habit: acicular to prismatic crystals.

Often confused with

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

mineral

Euxenite

Mohs 5.5-6.5

How to tell apart: Euxenite is the harder of the two (Mohs 5.5-6.5 vs. 3-4); streak differs — Carlosbarbosaite leaves pale yellow, Euxenite leaves yellowish, grayish, or reddish-brown; luster reads vitreous on Carlosbarbosaite and submetallic, resinous, greasy on Euxenite.

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Often found alongside carlosbarbosaite

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

All properties

Chemical formula: (UO₂)(Nb,Ta)₂O₆·2H₂O
Mohs hardness: 3-4
Density: 5.59 g/cm³
Colors: Yellow Yellowish-orange
Streak: Pale Yellow
Luster: Vitreous
Transparency: Translucent
Crystal system: Orthorhombic
Crystal habit: Acicular to Prismatic Crystals
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Granite Pegmatites
Typical price: $50-300 per specimen

Where rockhounds find carlosbarbosaite

Classic worldwide localities

Carlos Barbosa, Rio Grande do Sul, Brazil

Field-hunting tip

Look in granite pegmatites country — that is the host setting where carlosbarbosaite typically forms. If you start seeing quartz, microcline, albite in float, you are in the right ground. Field specimens usually show a acicular to prismatic crystals habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify carlosbarbosaite?+

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

Where is carlosbarbosaite found?+

Notable localities include Carlos Barbosa, Rio Grande do Sul, Brazil.

How much is carlosbarbosaite 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.

Is carlosbarbosaite safe to handle?+

This mineral is radioactive. Contains uranium; handle with care, store in a dedicated container, and wash hands thoroughly after handling to prevent ingestion of radioactive dust. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like carlosbarbosaite?+

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

What minerals are found with carlosbarbosaite?+

Carlosbarbosaite commonly co-occurs with Quartz, Microcline, Albite, Muscovite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does carlosbarbosaite form in?+

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

What is carlosbarbosaite used for?+

Carlosbarbosaite is used in collector.

Find carlosbarbosaite on the map

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