Galloplumbogummite is an exceptionally rare member of the plumbogummite group, forming as a secondary mineral in lead-rich oxidation zones. It is most commonly found as small, dull, yellowish-brown encrustations or botryoidal masses, often misidentified without micro-analysis due to its similarity to other group members.

Hardness

4-5

Mohs

Streak

White

Transparency

Transparent

mineralrarePlumbogummite Group family

Galloplumbogummite

Hardness: 4-5
Streak: White
Transparency: Transparent

Is this galloplumbogummite?

4-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 galloplumbogummite with a known reference. Galloplumbogummite sits at Mohs 4-5, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: white.
3
Match the color range
Compare against the expected color range: colorless, frosted white.
4
Look at form & habit
Crystal system: trigonal. Typical habit: massive, crusts, botryoidal.

Often confused with

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

Often found alongside galloplumbogummite

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

All properties

Chemical formula: Pb(Ga,Al)₂Ge(PO₄)₂(OH)₆
Mohs hardness: 4-5
Density: 4.62 g/cm³
Colors: ColorlessFrosted white
Streak: White
Transparency: Transparent
Crystal system: Trigonal
Crystal habit: Massive, crusts, botryoidal
Rarity: Rare
Uses: Collector
Host rock: A secondary mineral derived by alteration of Ge-Ga minerals in the oxidized zone of a dolostone-hosted, polymetallic, hydrothermal deposit

Where rockhounds find galloplumbogummite

Classic worldwide localities

Second oxidation zone, Tsumeb mine, Tsumeb, Otjikoto Region, Namibia

Field-hunting tip

Where it forms: A secondary mineral derived by alteration of Ge-Ga minerals in the oxidized zone of a dolostone-hosted, polymetallic, hydrothermal deposit. If you start seeing germanite-renierite, chalcocite, cd-rich sphalerite in float, you are in the right ground. Typical habit: massive, crusts, botryoidal. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify galloplumbogummite?+

Mohs hardness is 4-5. The streak is white. Common colors include colorless, frosted white.

Where is galloplumbogummite found?+

Notable localities include Second oxidation zone, Tsumeb mine, Tsumeb, Otjikoto Region, Namibia.

Is galloplumbogummite safe to handle?+

Galloplumbogummite contains lead. Contains lead and gallium; wash hands after handling and avoid inhaling dust.

What rocks look like galloplumbogummite?+

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

What minerals are found with galloplumbogummite?+

Galloplumbogummite commonly co-occurs with Germanite-renierite, Chalcocite, Cd-rich sphalerite, Galena, Pyrite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does galloplumbogummite form in?+

Where it forms: A secondary mineral derived by alteration of Ge-Ga minerals in the oxidized zone of a dolostone-hosted, polymetallic, hydrothermal deposit. Working float back to the host body is the standard way to chase a fresh occurrence.

What is galloplumbogummite used for?+

Galloplumbogummite is used in collector.

Find galloplumbogummite on the map

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