Watanabeite is a rare copper arsenic sulfosalt usually found as microscopic grains within hydrothermal ore deposits. It is best identified through laboratory analysis of associated epithermal mineralization, as it rarely forms distinct macroscopic crystals of interest to field collectors.

Hardness

4-4.5

Mohs

Luster

Metallic

Streak

Lead-gray

Transparency

Opaque

mineralrare

Watanabeite

Hardness: 4-4.5
Luster: Metallic
Streak: Lead-gray
Transparency: Opaque

Is this watanabeite?

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 watanabeite with a known reference. Watanabeite sits at Mohs 4-4.5, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: lead-gray.
3
Read the luster
Hold the specimen under a strong light. Luster: metallic.
4
Match the color range
Compare against the expected color range: lead gray, silver gray.
5
Look at form & habit
Crystal system: orthorhombic. Typical habit: anhedral grains, microscopic crystals.

Often confused with

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

mineral

Tetrahedrite

Mohs 3-4.5

How to tell apart: Streak differs, so Watanabeite leaves lead-gray, Tetrahedrite leaves black to brown.

How to tell apart: Watanabeite is noticeably harder (Mohs 4-4.5 vs. 3); streak differs, so Watanabeite leaves lead-gray, Enargite leaves grayish black.

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Often found alongside watanabeite

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

All properties

Chemical formula: Cu₄(As,Sb)₂S₅
Mohs hardness: 4-4.5
Density: 4.66 g/cm³
Colors: Lead gray Silver gray
Streak: Lead-gray
Luster: Metallic
Transparency: Opaque
Crystal system: Orthorhombic
Crystal habit: Anhedral grains, microscopic crystals
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: In a hydrothermal quartz vein (Teine mine); in a high sulfidation epithermal deposit (Kamchatka)

Where rockhounds find watanabeite

Classic worldwide localities

Teine mine, Sapporo, Hokkaido, Japan (type locality)
Maletoyvayam ore field, Kamchatka, Russia

Field-hunting tip

Where it forms: In a hydrothermal quartz vein (Teine mine); in a high sulfidation epithermal deposit (Kamchatka). If you start seeing emplectite, native bismuth, tennantite in float, you are in the right ground. Typical habit: anhedral grains, microscopic crystals. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify watanabeite?+

Mohs hardness is 4-4.5. Luster: metallic. The streak is lead-gray. Common colors include lead gray, silver gray.

Where is watanabeite found?+

Notable localities include Teine mine, Sapporo, Hokkaido, Japan (type locality); Maletoyvayam ore field, Kamchatka, Russia.

Is watanabeite safe to handle?+

Watanabeite contains antimony, arsenic and copper and calls for real care. Contains arsenic and copper; avoid inhalation of dust and handle with caution to prevent ingestion. Wash hands thoroughly after handling.

What rocks look like watanabeite?+

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

What minerals are found with watanabeite?+

Watanabeite commonly co-occurs with Emplectite, Native bismuth, Tennantite, Quartz. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does watanabeite form in?+

Where it forms: In a hydrothermal quartz vein (Teine mine); in a high sulfidation epithermal deposit (Kamchatka). Working float back to the host body is the standard way to chase a fresh occurrence.

What is watanabeite used for?+

Watanabeite is used in collector.

Find watanabeite on the map

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