Esperanzaite is a rare secondary arsenate mineral found in hydrothermal tin deposits. It typically forms small, clear to yellowish tabular crystals or radiating sprays on a matrix of host ore minerals.

Hardness

3-4

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrare

Esperanzaite

Hardness: 3-4
Luster: Vitreous
Streak: White
Transparency: Transparent

No image

Is this esperanzaite?

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

Often confused with

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

mineral

Pharmacosiderite

Mohs 2.5

How to tell apart: Luster reads vitreous on Esperanzaite and adamantine on Pharmacosiderite.

How to tell apart: Luster reads vitreous on Esperanzaite and vitreous to sub-adamantine on Scorodite.

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Often found alongside esperanzaite

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

All properties

Chemical formula: NaCaAl₂(AsO₄)₂F₄·2H₂O
Mohs hardness: 3-4
Density: 3.37 g/cm³
Colors: Yellow Yellowish-green Colorless
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Monoclinic
Crystal habit: Tabular Crystals, Radiating Aggregates, Crusts
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Hydrothermal Tin Deposits
Typical price: $50-500 depending on crystal size and quality

Where rockhounds find esperanzaite

Classic worldwide localities

Llallagua, Bolivia

Field-hunting tip

Look in hydrothermal tin deposits country, the host setting where esperanzaite typically forms. If you start seeing arsenopyrite, cassiterite, wavellite in float, you are in the right ground. Field specimens usually show a tabular crystals, radiating aggregates, crusts habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify esperanzaite?+

Mohs hardness is 3-4. It typically shows a vitreous luster. The streak is white. Common colors include yellow, yellowish-green, colorless.

Where is esperanzaite found?+

Notable localities include Llallagua, Bolivia.

How much is esperanzaite worth?+

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

Is esperanzaite safe to handle?+

It contains toxic constituents. Contains arsenic. Handle with care, wash hands thoroughly after contact, and avoid creating dust when cleaning specimens. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like esperanzaite?+

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

What minerals are found with esperanzaite?+

Esperanzaite commonly co-occurs with Arsenopyrite, Cassiterite, Wavellite, Paravauxite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does esperanzaite form in?+

Esperanzaite typically forms in hydrothermal tin deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

What is esperanzaite used for?+

Esperanzaite is used in collector.

Find esperanzaite on the map

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