Congolite is a rare member of the boracite group typically found in salt dome environments. Collectors should look for its distinctive pseudo-cubic trigonal crystals, which are frequently associated with potash-bearing evaporite sequences.

Hardness

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrareBoracite Group family

Congolite

Hardness: 7
Luster: Vitreous
Streak: White
Transparency: Transparent

Is this congolite?

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 congolite with a known reference. Congolite sits at Mohs 7 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Congolite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Congolite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: white, colorless, gray, pale pink.
5
Look at form & habit
Crystal system: trigonal. Typical habit: equant pseudo-cubic crystals, massive.

Often confused with

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

Often found alongside congolite

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

All properties

Chemical formula: Fe₃Mg₃(B₇O₁₃)Cl
Mohs hardness: 7
Density: 3.31 g/cm³
Colors: White Colorless Gray Pale Pink
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Trigonal
Crystal habit: Equant Pseudo-cubic Crystals, Massive
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Evaporite Deposits
Typical price: $50-300 per specimen

Where rockhounds find congolite

Classic worldwide localities

Republic of the Congo
Kazakhstan
Russia

Field-hunting tip

Look in evaporite deposits country — that is the host setting where congolite typically forms. If you start seeing halite, sylvite, carnallite in float, you are in the right ground. Field specimens usually show a equant pseudo-cubic crystals, massive habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify congolite?+

Mohs hardness is 7. It typically shows a vitreous luster. The streak is white. Common colors include white, colorless, gray, pale pink.

Where is congolite found?+

Notable localities include Republic of the Congo; Kazakhstan; Russia.

How much is congolite 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 congolite?+

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

What minerals are found with congolite?+

Congolite commonly co-occurs with Halite, Sylvite, Carnallite, Anhydrite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does congolite form in?+

Congolite typically forms in evaporite deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

What is congolite used for?+

Congolite is used in collector.

Find congolite on the map

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