Althupite is a complex secondary uranium mineral that forms thin, platy yellow to yellow-green crystals, often found in radiating clusters. It is an extremely rare phosphate species primarily known from the oxidized zones of uranium-bearing pegmatites in the Democratic Republic of the Congo. Due to its radioactive nature and scarcity, it is sought after primarily by advanced radioactive mineral collectors.

Hardness

3.5-4

Mohs

Luster

Vitreous

Streak

Yellow white

Transparency

Transparent

mineralrare

Althupite

Hardness: 3.5-4
Luster: Vitreous
Streak: Yellow white
Transparency: Transparent

Is this althupite?

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 althupite with a known reference. Althupite sits at Mohs 3.5-4, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: yellow white.
3
Read the luster
Hold the specimen under a strong light. Luster: vitreous.
4
Match the color range
Compare against the expected color range: yellow.
5
Look at form & habit
Crystal system: triclinic. Typical habit: platy crystals, radial aggregates.

Often confused with

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

mineral

Autunite

Mohs 2-2.5

How to tell apart: Althupite is noticeably harder (Mohs 3.5-4 vs. 2-2.5); streak differs, so Althupite leaves yellow white, Autunite leaves pale yellow.

How to tell apart: Althupite is noticeably harder (Mohs 3.5-4 vs. 2-2.5); streak differs, so Althupite leaves yellow white, Torbernite leaves pale green.

Compare →

Often found alongside althupite

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

All properties

Chemical formula: AlTh(UO₂)₇(PO₄)₄O₂(OH)₅·15H₂O
Mohs hardness: 3.5-4
Density: 3.9 g/cm³
Colors: Yellow
Streak: Yellow white
Luster: Vitreous
Transparency: Transparent
Crystal system: Triclinic
Crystal habit: Platy crystals, radial aggregates
Cleavage: Good
Rarity: Rare
Uses: Collector
Host rock: A secondary mineral in the uraniferous zone of an altered granite pegmatite

Where rockhounds find althupite

Classic worldwide localities

Kobokobo pegmatite, Lusungu River district, Kivu Province, Congo (Zaire)

Field-hunting tip

Where it forms: A secondary mineral in the uraniferous zone of an altered granite pegmatite. If you start seeing beryl, columbite, ranunculite in float, you are in the right ground. Typical habit: platy crystals, radial aggregates. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify althupite?+

Mohs hardness is 3.5-4. Luster: vitreous. The streak is yellow white. Common colors include yellow.

Where is althupite found?+

Notable localities include Kobokobo pegmatite, Lusungu River district, Kivu Province, Congo (Zaire).

Is althupite safe to handle?+

Althupite contains uranium or thorium and calls for real care. Althupite contains uranium and thorium, making it radioactive. Handle with care, wear gloves, avoid inhalation of dust, and store in a lead-lined container away from living spaces.

What rocks look like althupite?+

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

What minerals are found with althupite?+

Althupite commonly co-occurs with Beryl, Columbite, Ranunculite, Upalite, Phuralumite, Threadgoldite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does althupite form in?+

Where it forms: A secondary mineral in the uraniferous zone of an altered granite pegmatite. Working float back to the host body is the standard way to chase a fresh occurrence.

What is althupite used for?+

Althupite is used in collector.

Find althupite on the map

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