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

3.5

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrareGorceixite Group family

Tapiaite

Hardness: 3.5
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 3.5 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Tapiaite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Tapiaite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: colorless, white, yellow.
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. 3.5); streak differs — Tapiaite leaves white, Conichalcite leaves light green.

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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: CaZn₂(AsO₄)₂(OH)₂
Mohs hardness: 3.5
Density: 3.66 g/cm³
Colors: Colorless White Yellow
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Monoclinic
Crystal habit: Tabular Crystals, Radiating Aggregates
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Oxidized Hydrothermal Lead-zinc-arsenic Ore Deposits
Typical price: $50-300 per specimen depending on size and crystal quality

Where rockhounds find tapiaite

Classic worldwide localities

Ojuela Mine, Mapimi, Durango, Mexico

Field-hunting tip

Look in oxidized hydrothermal lead-zinc-arsenic ore deposits country — that is the host setting where tapiaite typically forms. If you start seeing arseniosiderite, adamite, legrandite in float, you are in the right ground. Field specimens usually show a tabular crystals, radiating aggregates habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify tapiaite?+

Mohs hardness is 3.5. It typically shows a vitreous luster. The streak is white. Common colors include colorless, white, yellow.

Where is tapiaite found?+

Notable localities include Ojuela Mine, Mapimi, Durango, Mexico.

How much is tapiaite worth?+

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

Is tapiaite safe to handle?+

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

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 Arseniosiderite, Adamite, Legrandite, Smithsonite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does tapiaite form in?+

Tapiaite typically forms in oxidized hydrothermal lead-zinc-arsenic ore deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

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.