Arsenohopeite is a rare hydrated zinc arsenate found in the oxidized zones of base metal deposits. It typically forms as small, colorless to white tabular crystals that are visually indistinguishable from its phosphate analog, Hopeite, without chemical analysis.

Hardness

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrareHopeite Group family

Arsenohopeite

Hardness: 3
Luster: Vitreous
Streak: White
Transparency: Transparent

No image

Is this arsenohopeite?

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 arsenohopeite with a known reference. Arsenohopeite sits at Mohs 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, blue.
5
Look at form & habit
Crystal system: orthorhombic. Typical habit: tabular crystals.

Often confused with

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

Often found alongside arsenohopeite

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

All properties

Chemical formula: Zn₃(AsO₄)₂·4H₂O
Mohs hardness: 3
Density: 3.42 g/cm³
Colors: Colorless Blue
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Orthorhombic
Crystal habit: Tabular crystals
Cleavage: Perfect on {010}, good on {100}, poor on 01} (by analogy with hopeite)
Rarity: Rare
Uses: Collector
Host rock: A rare secondary mineral formed by alteration of tennantite-rich ore in the oxidized zone of a dolostone-hosted, polymetallic, hydrothermal ore deposit

Where rockhounds find arsenohopeite

Classic worldwide localities

Tsumeb, Namibia

Field-hunting tip

Where it forms: A rare secondary mineral formed by alteration of tennantite-rich ore in the oxidized zone of a dolostone-hosted, polymetallic, hydrothermal ore deposit. If you start seeing köttigite, adamite, leiteite in float, you are in the right ground. Typical habit: tabular crystals. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify arsenohopeite?+

Mohs hardness is 3. Luster: vitreous. The streak is white. Common colors include colorless, blue.

Where is arsenohopeite found?+

Notable localities include Tsumeb, Namibia.

Is arsenohopeite safe to handle?+

Arsenohopeite contains arsenic and calls for real care. Contains arsenic, a toxic element. Handle with care, avoid inhalation of dust, and wash hands thoroughly after handling.

What rocks look like arsenohopeite?+

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

What minerals are found with arsenohopeite?+

Arsenohopeite commonly co-occurs with Köttigite, Adamite, Leiteite, Schneiderhöhnite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does arsenohopeite form in?+

Where it forms: A rare secondary mineral formed by alteration of tennantite-rich ore in the oxidized zone of a dolostone-hosted, polymetallic, hydrothermal ore deposit. Working float back to the host body is the standard way to chase a fresh occurrence.

What is arsenohopeite used for?+

Arsenohopeite is used in collector.

Find arsenohopeite on the map

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