Otwayite is a rare nickel carbonate mineral that typically appears as bright green, fibrous crusts or micro-crystalline aggregates. It is most commonly found in the oxidized zones of nickel sulfide deposits in Western Australia, often associated with other rare nickel minerals like gaspeite. Due to its scarcity and distinct coloration, it is highly sought after by systematic mineral collectors.

Hardness

2.5

Mohs

Luster

Dull

Streak

Pale Green

Transparency

Opaque

mineralrare

Otwayite

Hardness: 2.5
Luster: Dull
Streak: Pale Green
Transparency: Opaque

Is this otwayite?

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 otwayite with a known reference. Otwayite sits at Mohs 2.5 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Otwayite leaves a pale green streak.
3
Read the luster
Hold the specimen under a strong light. Otwayite typically shows a dull luster.
4
Match the color range
Compare against the expected color range: bright green, pale green.
5
Look at form & habit
Crystal system: orthorhombic. Typical habit: crusts, aggregates, fibrous.

Often confused with

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

mineral

Zaratite

Mohs 3-3.25

How to tell apart: Luster reads dull on Otwayite and vitreous on Zaratite.

Compare →

Often found alongside otwayite

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

All properties

Chemical formula: Ni₂(CO₃)(OH)₂
Mohs hardness: 2.5
Density: 3.5 g/cm³
Colors: Bright Green Pale Green
Streak: Pale Green
Luster: Dull
Transparency: Opaque
Crystal system: Orthorhombic
Crystal habit: Crusts, Aggregates, Fibrous
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Oxidized Zones of Nickel Sulfide Deposits
Typical price: $50-300 per specimen

Where rockhounds find otwayite

Classic worldwide localities

Otway deposit, Kambalda, Western Australia
Widgiemooltha, Western Australia

Field-hunting tip

Look in oxidized zones of nickel sulfide deposits country — that is the host setting where otwayite typically forms. If you start seeing gaspeite, millerite, magnesite in float, you are in the right ground. Field specimens usually show a crusts, aggregates, fibrous habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify otwayite?+

Mohs hardness is 2.5. It typically shows a dull luster. The streak is pale green. Common colors include bright green, pale green.

Where is otwayite found?+

Notable localities include Otway deposit, Kambalda, Western Australia; Widgiemooltha, Western Australia.

How much is otwayite 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 otwayite safe to handle?+

It contains toxic constituents. Contains nickel, which is a toxic heavy metal; wash hands thoroughly after handling specimens and avoid inhaling dust. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like otwayite?+

Otwayite is most often confused with Zaratite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with otwayite?+

Otwayite commonly co-occurs with Gaspeite, Millerite, Magnesite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does otwayite form in?+

Otwayite typically forms in oxidized zones of nickel sulfide deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

What is otwayite used for?+

Otwayite is used in collector.

Find otwayite on the map

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