Carboirite is an extremely rare iron aluminum germanium hydroxide mineral primarily found in the complex sulfide ores of the Tsumeb Mine. It typically presents as small, dark, opaque tabular crystals associated with other rare germanium-bearing species. It is a highly sought-after prize for advanced mineral collectors specializing in rare sulfides and oxides.

Hardness

5-6

Mohs

Luster

Submetallic

Streak

Black

Transparency

Opaque

mineralrare

Carboirite

Hardness: 5-6
Luster: Submetallic
Streak: Black
Transparency: Opaque

Is this carboirite?

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 carboirite with a known reference. Carboirite sits at Mohs 5-6 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Carboirite leaves a black streak.
3
Read the luster
Hold the specimen under a strong light. Carboirite typically shows a submetallic luster.
4
Match the color range
Compare against the expected color range: black, dark brown.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: tabular crystals, massive.

Often confused with

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

How to tell apart: Streak differs — Carboirite leaves black, Iron Ore leaves reddish-brown to black; luster reads submetallic on Carboirite and metallic to submetallic on Iron Ore.

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Often found alongside carboirite

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

All properties

Chemical formula: FeAl₂GeO₅(OH)₂
Mohs hardness: 5-6
Density: 4.15 g/cm³
Colors: Black Dark Brown
Streak: Black
Luster: Submetallic
Transparency: Opaque
Crystal system: Monoclinic
Crystal habit: Tabular Crystals, Massive
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Hydrothermal Polymetallic Deposits
Typical price: $50-300 per specimen

Where rockhounds find carboirite

Classic worldwide localities

Tsumeb Mine, Namibia

Field-hunting tip

Look in hydrothermal polymetallic deposits country — that is the host setting where carboirite typically forms. If you start seeing germanite, renierite, tennantite in float, you are in the right ground. Field specimens usually show a tabular crystals, massive habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify carboirite?+

Mohs hardness is 5-6. It typically shows a submetallic luster. The streak is black. Common colors include black, dark brown.

Where is carboirite found?+

Notable localities include Tsumeb Mine, Namibia.

How much is carboirite 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.

What rocks look like carboirite?+

Carboirite is most often confused with Manaccanite, Iron Ore. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with carboirite?+

Carboirite commonly co-occurs with Germanite, Renierite, Tennantite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does carboirite form in?+

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

What is carboirite used for?+

Carboirite is used in collector.

Find carboirite on the map

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