Amarillite is an extremely rare thallium-bearing sulfate mineral primarily known from the copper mines of northern Chile. It typically forms as delicate, pale yellow prismatic crystals or crusts within the oxidized zones of ore deposits. Due to its thallium content and rarity, it is a specialized collector's mineral that requires careful handling.

Hardness

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrare

Amarillite

Hardness: 2
Luster: Vitreous
Streak: White
Transparency: Transparent

Is this amarillite?

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 amarillite with a known reference. Amarillite sits at Mohs 2 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Amarillite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Amarillite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: yellow, pale yellow.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: prismatic crystals, crusts.

Often confused with

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

mineral

Pickeringite

Mohs 1.5-2

How to tell apart: Luster reads vitreous on Amarillite and silky on Pickeringite.

Often found alongside amarillite

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

All properties

Chemical formula: NaTl(SO₄)₂·6H₂O
Mohs hardness: 2
Density: 2.33 g/cm³
Colors: Yellow Pale Yellow
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Monoclinic
Crystal habit: Prismatic Crystals, Crusts
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Oxidized Zones of Hydrothermal Ore Deposits
Typical price: $50-500 depending on specimen quality and size

Where rockhounds find amarillite

Classic worldwide localities

Chuquicamata, Chile

Field-hunting tip

Look in oxidized zones of hydrothermal ore deposits country — that is the host setting where amarillite typically forms. If you start seeing chalcanthite, copiapite, gypsum in float, you are in the right ground. Field specimens usually show a prismatic crystals, crusts habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify amarillite?+

Mohs hardness is 2. It typically shows a vitreous luster. The streak is white. Common colors include yellow, pale yellow.

Where is amarillite found?+

Notable localities include Chuquicamata, Chile.

How much is amarillite worth?+

Typical asking prices fall in the range of $50-500 depending on specimen quality and size. Quality, size, and provenance can move individual specimens well outside that range.

Is amarillite safe to handle?+

It contains toxic constituents. Contains thallium, a highly toxic heavy metal. Wash hands thoroughly after handling and avoid ingestion or inhalation of dust. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like amarillite?+

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

What minerals are found with amarillite?+

Amarillite commonly co-occurs with Chalcanthite, Copiapite, Gypsum. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does amarillite form in?+

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

What is amarillite used for?+

Amarillite is used in collector.

Find amarillite on the map

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