Espadaite is a rare sodium calcium magnesium arsenite, typically colorless. Associated minerals include camanchacaite, anhydrite and gypsum. It was first described from the Torrecillas mine, Iquique Province, Tarapacá Region, Chile.

Hardness

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrare

Espadaite

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

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Is this espadaite?

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 espadaite with a known reference. Espadaite 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. 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.
5
Look at form & habit
Crystal system: orthorhombic. Typical habit: platy crystals.

Often confused with

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

mineral

Fairfieldite

Mohs 3.5

How to tell apart: Fairfieldite is the harder of the two (Mohs 3.5 vs. ~2); luster reads vitreous on Espadaite and pearly to subadamantine, vitreous on the {001} cleavage on Fairfieldite.

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Often found alongside espadaite

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

All properties

Chemical formula: Na₄Ca₃Mg₂[AsO₃(OH)]₂[AsO₂(OH)₂]₁₀(H₂O)₆·H₂O
Mohs hardness: ~2
Density: 2.73 g/cm³
Colors: Colorless
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Orthorhombic
Crystal habit: Platy crystals
Cleavage: Perfect on {001}
Rarity: Rare
Uses: Collector
Host rock: granite pegmatites

Where rockhounds find espadaite

Classic worldwide localities

Torrecillas mine, northern Atacama Desert, Salar Grande, Iquique Province, Tarapacá Region, Chile

Field-hunting tip

Where it forms: granite pegmatites. If you start seeing camanchacaite, anhydrite, gypsum in float, you are in the right ground. Typical habit: platy crystals. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify espadaite?+

Mohs hardness is ~2. Luster: vitreous. The streak is white. Common colors include colorless.

Where is espadaite found?+

Notable localities include Torrecillas mine, northern Atacama Desert, Salar Grande, Iquique Province, Tarapacá Region, Chile.

Is espadaite safe to handle?+

Espadaite contains arsenic and calls for real care. Contains arsenic, which is toxic if ingested or inhaled as dust. Wash hands thoroughly after handling and avoid creating dust.

What rocks look like espadaite?+

Espadaite is most often confused with Fairfieldite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with espadaite?+

Espadaite commonly co-occurs with Camanchacaite, Anhydrite, Gypsum, Halite, Talmessite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does espadaite form in?+

Where it forms: granite pegmatites. Working float back to the host body is the standard way to chase a fresh occurrence.

What is espadaite used for?+

Espadaite is used in collector.

Find espadaite on the map

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