Juansilvaite is an extremely rare arsenic-bearing silicate mineral discovered at the Torrecillas mine in Chile. It typically forms thin, platy, colorless to white crystal aggregates associated with other rare arsenic-rich species.

Hardness

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrare

Juansilvaite

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

Is this juansilvaite?

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 juansilvaite with a known reference. Juansilvaite 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. Juansilvaite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Juansilvaite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: white, colorless.
5
Look at form & habit
Crystal system: orthorhombic. Typical habit: platy crystals, crusts.

Often confused with

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

mineral

Aragonite

Mohs 3.5-4

How to tell apart: Aragonite is the harder of the two (Mohs 3.5-4 vs. 2).

Often found alongside juansilvaite

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

All properties

Chemical formula: Na₂Al₂As₂Si₂O₁₀(OH)₄·4H₂O
Mohs hardness: 2
Density: 2.16 g/cm³
Colors: White Colorless
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Orthorhombic
Crystal habit: Platy Crystals, Crusts
Cleavage: Perfect
Rarity: Rare
Uses: Collector
Host rock: Hydrothermal Veins in Sedimentary Rocks
Typical price: $50-300+ per specimen

Where rockhounds find juansilvaite

Classic worldwide localities

Torrecillas mine, Chile

Field-hunting tip

Look in hydrothermal veins in sedimentary rocks country — that is the host setting where juansilvaite typically forms. If you start seeing realgar, arsenolite, leucophanite in float, you are in the right ground. Field specimens usually show a platy crystals, crusts habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify juansilvaite?+

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

Where is juansilvaite found?+

Notable localities include Torrecillas mine, Chile.

How much is juansilvaite worth?+

Typical asking prices fall in the range of $50-300+ per specimen. Quality, size, and provenance can move individual specimens well outside that range.

Is juansilvaite safe to handle?+

It contains toxic constituents. Contains arsenic, a toxic element. Wash hands thoroughly after handling and do not ingest or inhale dust. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like juansilvaite?+

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

What minerals are found with juansilvaite?+

Juansilvaite commonly co-occurs with realgar, arsenolite, leucophanite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does juansilvaite form in?+

Juansilvaite typically forms in hydrothermal veins in sedimentary rocks. Working float back to the host body is the standard way to chase a fresh occurrence.

What is juansilvaite used for?+

Juansilvaite is used in collector.

Find juansilvaite on the map

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