Otjisumeite is an extremely rare lead-germanium oxide found almost exclusively in the Tsumeb Mine in Namibia. Collectors prize its distinct pale yellow tabular crystal form, which typically occurs in association with complex sulfide ores.

Hardness

Mohs

Luster

Greasy to Subadamantine

Streak

White

Transparency

Transparent

mineralrare

Otjisumeite

Hardness: 3
Luster: Greasy to Subadamantine
Streak: White
Transparency: Transparent

Is this otjisumeite?

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 otjisumeite with a known reference. Otjisumeite 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. Otjisumeite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Otjisumeite typically shows a greasy to subadamantine luster.
4
Match the color range
Compare against the expected color range: colorless, white.
5
Look at form & habit
Crystal system: triclinic. Typical habit: tabular crystals, radiating aggregates.

Often confused with

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

mineral

Anglesite

Mohs 2.5-3

How to tell apart: Luster reads greasy to subadamantine on Otjisumeite and adamantine on Anglesite.

How to tell apart: Luster reads greasy to subadamantine on Otjisumeite and adamantine on Cerussite.

Compare →

Often found alongside otjisumeite

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

All properties

Chemical formula: PbGe₄O₉
Mohs hardness: 3
Density: 6.08 g/cm³
Colors: Colorless White
Streak: White
Luster: Greasy to Subadamantine
Transparency: Transparent
Crystal system: Triclinic
Crystal habit: Tabular Crystals, Radiating Aggregates
Cleavage: Good
Rarity: Rare
Uses: Collector
Host rock: Hydrothermal Polymetallic Deposits

Where rockhounds find otjisumeite

Classic worldwide localities

Tsumeb Mine, Namibia

Field-hunting tip

Look in hydrothermal polymetallic deposits country, the host setting where otjisumeite typically forms. If you start seeing galena, germanite, renierite 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 otjisumeite?+

Mohs hardness is 3. It typically shows a greasy to subadamantine luster. The streak is white. Common colors include colorless, white.

Where is otjisumeite found?+

Notable localities include Tsumeb Mine, Namibia.

Is otjisumeite safe to handle?+

It contains toxic constituents. Contains lead and germanium. Wash hands thoroughly after handling and do not ingest or inhale dust. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like otjisumeite?+

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

What minerals are found with otjisumeite?+

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

What kind of rock does otjisumeite form in?+

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

What is otjisumeite used for?+

Otjisumeite is used in collector.

Find otjisumeite on the map

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