Vendidaite is an extremely rare aluminum sulfate mineral found primarily in arid, oxidized mineral environments. It typically occurs as thin crusts or granular aggregates, often identified by its distinct yellowish color and association with other secondary sulfate minerals. Due to its rarity, it is almost exclusively sought after by advanced systematic mineral collectors.

Hardness

Mohs

Luster

Resinous

Streak

Yellow

Transparency

Translucent

mineralrare

Vendidaite

Hardness: 3
Luster: Resinous
Streak: Yellow
Transparency: Translucent

Is this vendidaite?

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 vendidaite with a known reference. Vendidaite 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. Vendidaite leaves a yellow streak.
3
Read the luster
Hold the specimen under a strong light. Vendidaite typically shows a resinous luster.
4
Match the color range
Compare against the expected color range: yellow, yellow-brown.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: crusts, granular.

Often confused with

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

mineral

Alunite

Mohs 3.5-4

How to tell apart: Streak differs — Vendidaite leaves yellow, Alunite leaves white; luster reads resinous on Vendidaite and vitreous on Alunite.

How to tell apart: Luster reads resinous on Vendidaite and vitreous on Jarosite.

Compare →

Often found alongside vendidaite

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

All properties

Chemical formula: Al₂SO₄(OH)₄·2H₂O
Mohs hardness: 3
Density: 2.83 g/cm³
Colors: Yellow Yellow-brown
Streak: Yellow
Luster: Resinous
Transparency: Translucent
Crystal system: Monoclinic
Crystal habit: Crusts, Granular
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Oxidized Ore Deposits
Typical price: $20-100 for small study specimens

Where rockhounds find vendidaite

Classic worldwide localities

Vendida mine, Sierra Gorda, Chile

Field-hunting tip

Look in oxidized ore deposits country — that is the host setting where vendidaite typically forms. If you start seeing gypsum, jarosite, alunite in float, you are in the right ground. Field specimens usually show a crusts, granular habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify vendidaite?+

Mohs hardness is 3. It typically shows a resinous luster. The streak is yellow. Common colors include yellow, yellow-brown.

Where is vendidaite found?+

Notable localities include Vendida mine, Sierra Gorda, Chile.

How much is vendidaite worth?+

Typical asking prices fall in the range of $20-100 for small study specimens. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like vendidaite?+

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

What minerals are found with vendidaite?+

Vendidaite commonly co-occurs with Gypsum, Jarosite, Alunite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does vendidaite form in?+

Vendidaite typically forms in oxidized ore deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

What is vendidaite used for?+

Vendidaite is used in collector.

Find vendidaite on the map

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