Roxbyite is a rare copper sulfide mineral primarily identified through X-ray diffraction due to its visual similarity to chalcocite. It typically occurs as massive aggregates in copper-rich ore bodies, often found associated with other copper sulfide minerals in hydrothermal systems.

Hardness

2.5-3

Mohs

Luster

Metallic

Streak

Black

Transparency

Opaque

mineralrare

Roxbyite

Hardness: 2.5-3
Luster: Metallic
Streak: Black
Transparency: Opaque

Is this roxbyite?

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 roxbyite with a known reference. Roxbyite sits at Mohs 2.5-3, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Roxbyite leaves a black streak.
3
Read the luster
Hold the specimen under a strong light. Roxbyite typically shows a metallic luster.
4
Match the color range
Compare against the expected color range: dark gray, black.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: massive.

Often confused with

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

mineral

Chalcocite

Mohs 2.5-3

How to tell apart: Streak differs, so Roxbyite leaves black, Chalcocite leaves lead-gray to black.

Often found alongside roxbyite

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

All properties

Chemical formula: Cu₁.₇₈S
Mohs hardness: 2.5-3
Density: 5.68 g/cm³
Colors: Dark Gray Black
Streak: Black
Luster: Metallic
Transparency: Opaque
Crystal system: Monoclinic
Crystal habit: Massive
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Hydrothermal Copper Deposits
Typical price: $50-300 per specimen

Where rockhounds find roxbyite

Classic worldwide localities

Olympic Dam mine, South Australia
Leonard mine, Butte, Montana, USA

Field-hunting tip

Look in hydrothermal copper deposits country, the host setting where roxbyite typically forms. If you start seeing chalcocite, digenite, bornite in float, you are in the right ground. Field specimens usually show a massive habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify roxbyite?+

Mohs hardness is 2.5-3. It typically shows a metallic luster. The streak is black. Common colors include dark gray, black.

Where is roxbyite found?+

Notable localities include Olympic Dam mine, South Australia; Leonard mine, Butte, Montana, USA.

How much is roxbyite 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 roxbyite safe to handle?+

It contains toxic constituents. Contains copper and sulfur; wash hands after handling and avoid inhaling dust. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like roxbyite?+

Roxbyite is most often confused with Chalcocite, Digenite, Anilite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with roxbyite?+

Roxbyite commonly co-occurs with Chalcocite, Digenite, Bornite, Chalcopyrite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does roxbyite form in?+

Roxbyite typically forms in hydrothermal copper deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

What is roxbyite used for?+

Roxbyite is used in collector.

Find roxbyite on the map

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