Zaccariniite is a rare platinum-group mineral typically occurring as microscopic grains within chromite deposits. Collectors rarely encounter it except as micro-inclusions in platinum-group alloy suites found in ophiolitic complexes.

Hardness

3.5-4

Mohs

Luster

Metallic

Streak

Gray

Transparency

Opaque

mineralrare

Zaccariniite

Hardness: 3.5-4
Luster: Metallic
Streak: Gray
Transparency: Opaque

No image

Is this zaccariniite?

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 zaccariniite with a known reference. Zaccariniite sits at Mohs 3.5-4, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Zaccariniite leaves a gray streak.
3
Read the luster
Hold the specimen under a strong light. Zaccariniite typically shows a metallic luster.
4
Match the color range
Compare against the expected color range: white, silver-white.
5
Look at form & habit
Crystal system: tetragonal. Typical habit: anhedral grains.

Often confused with

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

mineral

Sperrylite

Mohs 6-7

How to tell apart: Sperrylite is the harder of the two (Mohs 6-7 vs. 3.5-4); streak differs, so Zaccariniite leaves gray, Sperrylite leaves black.

How to tell apart: Laurite is the harder of the two (Mohs 7-7.5 vs. 3.5-4); streak differs, so Zaccariniite leaves gray, Laurite leaves dark gray.

How to tell apart: Hollingworthite is the harder of the two (Mohs 6 vs. 3.5-4); streak differs, so Zaccariniite leaves gray, Hollingworthite leaves grayish-black.

Compare →

Often found alongside zaccariniite

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

All properties

Chemical formula: RhNiAs
Mohs hardness: 3.5-4
Density: 10.09 g/cm³
Colors: White Silver-white
Streak: Gray
Luster: Metallic
Transparency: Opaque
Crystal system: Tetragonal
Crystal habit: Anhedral Grains
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Ophiolitic Chromitite Deposits

Where rockhounds find zaccariniite

Classic worldwide localities

Ophir Creek, Oregon, USA
Kempirsai Massif, Kazakhstan

Field-hunting tip

Look in ophiolitic chromitite deposits country, the host setting where zaccariniite typically forms. If you start seeing magnetite, chromite, laurite in float, you are in the right ground. Field specimens usually show a anhedral grains habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify zaccariniite?+

Mohs hardness is 3.5-4. It typically shows a metallic luster. The streak is gray. Common colors include white, silver-white.

Where is zaccariniite found?+

Notable localities include Ophir Creek, Oregon, USA; Kempirsai Massif, Kazakhstan.

Is zaccariniite safe to handle?+

It contains toxic constituents. Contains arsenic, which is toxic. Handle with care, wash hands after touching, and avoid creating dust. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like zaccariniite?+

Zaccariniite is most often confused with Sperrylite, Laurite, Hollingworthite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with zaccariniite?+

Zaccariniite commonly co-occurs with Magnetite, Chromite, Laurite, Irarsite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does zaccariniite form in?+

Zaccariniite typically forms in ophiolitic chromitite deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

What is zaccariniite used for?+

Zaccariniite is used in collector.

Find zaccariniite on the map

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