Tapiaite is a rare calcium-zinc arsenate mineral found in the oxidation zones of arsenic-rich ore deposits. It typically occurs as small, colorless to pale yellow, translucent tabular crystals or crusts often associated with other rare secondary arsenates.

Hardness

~2-3

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrareGorceixite Group family

Tapiaite

Hardness: ~2-3
Luster: Vitreous
Streak: White
Transparency: Transparent

Is this tapiaite?

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 tapiaite with a known reference. Tapiaite sits at Mohs ~2-3, 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: monoclinic. Typical habit: tabular crystals, radiating aggregates.

Often confused with

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

How to tell apart: Conichalcite is the harder of the two (Mohs 4.5 vs. ~2-3); streak differs, so Tapiaite leaves white, Conichalcite leaves green.

Compare →

Often found alongside tapiaite

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

All properties

Chemical formula: Ca₅Al₂(AsO₄)₄(OH)₄·12H₂O
Mohs hardness: ~2-3
Density: 2.681 g/cm³
Colors: Colorless
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Monoclinic
Crystal habit: Tabular crystals, radiating aggregates
Cleavage: Perfect on {101} and {101̄}
Rarity: Rare
Uses: Collector
Host rock: A late-stage, low-temperature, secondary mineral that occurs in narrow seams and vugs in the oxidized upper portion of a hydrothermal sulfide vein hosted by volcanoclastic rocks

Where rockhounds find tapiaite

Classic worldwide localities

Jote mine, Pampa Larga district, Tierra Amarilla, Copiapó Province, Atacama region, Chile

Field-hunting tip

Where it forms: A late-stage, low-temperature, secondary mineral that occurs in narrow seams and vugs in the oxidized upper portion of a hydrothermal sulfide vein hosted by volcanoclastic rocks. If you start seeing conichalcite, joteite, mansfieldite in float, you are in the right ground. Typical habit: tabular crystals, radiating aggregates. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify tapiaite?+

Mohs hardness is ~2-3. Luster: vitreous. The streak is white. Common colors include colorless.

Where is tapiaite found?+

Notable localities include Jote mine, Pampa Larga district, Tierra Amarilla, Copiapó Province, Atacama region, Chile.

Is tapiaite safe to handle?+

Tapiaite contains arsenic and calls for real care. Contains arsenic, a toxic element. Handle with care, avoid creating dust, and wash hands thoroughly after contact.

What rocks look like tapiaite?+

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

What minerals are found with tapiaite?+

Tapiaite commonly co-occurs with Conichalcite, Joteite, Mansfieldite, Pharmacoalumite, Pharmacosiderite, Scorodite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does tapiaite form in?+

What is tapiaite used for?+

Tapiaite is used in collector.

Find tapiaite on the map

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