Brüggenite is a rare calcium iodate mineral found exclusively in the hyper-arid nitrate deposits of the Atacama Desert. Collectors prize it for its sharp, transparent monoclinic crystals that are often found associated with other rare iodine-bearing species like dietzeite.

Hardness

3.5

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent to translucent

mineralrare

Brüggenite

Hardness: 3.5
Luster: Vitreous
Streak: White
Transparency: Transparent to translucent

Is this brüggenite?

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 brüggenite with a known reference. Brüggenite sits at Mohs 3.5, 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
Read the luster
Hold the specimen under a strong light. Luster: vitreous.
4
Match the color range
Compare against the expected color range: colorless, bright yellow.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: tabular crystals, subparallel aggregates.

Often confused with

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

mineral

Dietzeite

Mohs 3.5

How to tell apart: Streak differs, so Brüggenite leaves white, Dietzeite leaves light yellow.

Often found alongside brüggenite

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

All properties

Chemical formula: Ca(IO₃)₂·H₂O
Mohs hardness: 3.5
Density: 4.24 g/cm³
Colors: Colorless Bright yellow
Streak: White
Luster: Vitreous
Transparency: Transparent to translucent
Crystal system: Monoclinic
Crystal habit: Tabular crystals, subparallel aggregates
Cleavage: Perfect on {010}
Rarity: Rare
Uses: Collector, Scientific research
Host rock: In veins with nitratine and impregnating the enclosing decomposing rhyolite tuff in a small basin filled with nitrate caliche

Where rockhounds find brüggenite

Classic worldwide localities

Pampa Pique III, about one km north of Oficina Lautaro, Taltal district, Antofagasta, Chile

Field-hunting tip

Where it forms: In veins with nitratine and impregnating the enclosing decomposing rhyolite tuff in a small basin filled with nitrate caliche. If you start seeing nitratine, anhydrite, lautarite in float, you are in the right ground. Typical habit: tabular crystals, subparallel aggregates. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify brüggenite?+

Mohs hardness is 3.5. Luster: vitreous. The streak is white. Common colors include colorless, bright yellow.

Where is brüggenite found?+

Notable localities include Pampa Pique III, about one km north of Oficina Lautaro, Taltal district, Antofagasta, Chile.

What rocks look like brüggenite?+

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

What minerals are found with brüggenite?+

Brüggenite commonly co-occurs with Nitratine, Anhydrite, Lautarite, Hydroboracite, Halite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does brüggenite form in?+

Where it forms: In veins with nitratine and impregnating the enclosing decomposing rhyolite tuff in a small basin filled with nitrate caliche. Working float back to the host body is the standard way to chase a fresh occurrence.

What is brüggenite used for?+

Brüggenite is used in collector, scientific research.

Find brüggenite on the map

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