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, 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.