Taniajacoite is a rare copper-arsenic mineral characterized by its distinct green, platy crystal morphology. It is primarily found in the oxidized zones of copper-arsenic rich hydrothermal deposits, typically appearing as small, delicate clusters.

Hardness

3-4

Mohs

Luster

Vitreous

Streak

Pale Green

Transparency

Translucent

mineralrare

Taniajacoite

Hardness: 3-4
Luster: Vitreous
Streak: Pale Green
Transparency: Translucent

No image

Is this taniajacoite?

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 taniajacoite with a known reference. Taniajacoite 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. Taniajacoite leaves a pale green streak.
3
Read the luster
Hold the specimen under a strong light. Taniajacoite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: dark green, blackish-green.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: platy crystals.

Often confused with

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

mineral

Austinite

Mohs 4

How to tell apart: Streak differs, so Taniajacoite leaves pale green, Austinite leaves white.

How to tell apart: Streak differs, so Taniajacoite leaves pale green, Conichalcite leaves light green.

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All properties

Chemical formula: CaCu₄(AsO₄)₂(OH)₄·5H₂O
Mohs hardness: 3-4
Density: 2.95 g/cm³
Colors: Dark Green Blackish-green
Streak: Pale Green
Luster: Vitreous
Transparency: Translucent
Crystal system: Monoclinic
Crystal habit: Platy Crystals
Cleavage: Perfect
Rarity: Rare
Uses: Collector
Host rock: Hydrothermal Veins
Typical price: $50-300 per specimen

Where rockhounds find taniajacoite

Classic worldwide localities

Taniajaco mine, Mexico

Field-hunting tip

Look in hydrothermal veins country, the host setting where taniajacoite typically forms. If you start seeing arsenates, copper secondary minerals in float, you are in the right ground. Field specimens usually show a platy crystals habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify taniajacoite?+

Mohs hardness is 3-4. It typically shows a vitreous luster. The streak is pale green. Common colors include dark green, blackish-green.

Where is taniajacoite found?+

Notable localities include Taniajaco mine, Mexico.

How much is taniajacoite 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 taniajacoite safe to handle?+

It contains toxic constituents. Contains arsenic and copper; avoid ingestion, inhalation of dust, or skin contact. Wash hands thoroughly after handling. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like taniajacoite?+

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

What minerals are found with taniajacoite?+

Taniajacoite commonly co-occurs with Arsenates, Copper secondary minerals. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does taniajacoite form in?+

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

What is taniajacoite used for?+

Taniajacoite is used in collector.

Find taniajacoite on the map

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