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.
Is this roxbyite?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry 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.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: black.
- 3Read the lusterHold the specimen under a strong light. Luster: metallic to dull.
- 4Match the color rangeCompare against the expected color range: bluish black.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: aggregates, powdery.
Often confused with
Roxbyite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Roxbyite leaves black, Chalcocite leaves blackish lead-gray.
How to tell apart: Streak differs, so Roxbyite leaves black, Digenite leaves grayish black; luster reads metallic to dull on Roxbyite and submetallic on Digenite.
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
- 5.555 g/cm³
- Colors
- Streak
- Black
- Luster
- Metallic to dull
- Transparency
- Opaque
- Crystal system
- Monoclinic
- Crystal habit
- Aggregates, powdery
- Cleavage
- Poor on {100}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A low-temperature alteration product of djurleite, in a complex polymetallic hydrothermal deposit (Olympic Dam, Australia); in a porphyry copper deposit (El Teniente mine, Chile)
Where rockhounds find roxbyite
Classic worldwide localities
- Olympic Dam Cu–Au–U deposit, Roxby Downs Station, near Woomera, South Australia (type locality)
- El Teniente mine, 67 km west of Rancagua, O’Higgins Province, Chile
Field-hunting tip
Where it forms: A low-temperature alteration product of djurleite, in a complex polymetallic hydrothermal deposit (Olympic Dam, Australia); in a porphyry copper deposit (El Teniente mine, Chile). If you start seeing djurleite, bornite, pyrite in float, you are in the right ground. Typical habit: aggregates, powdery. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify roxbyite?+
Where is roxbyite found?+
Is roxbyite safe to handle?+
What rocks look like roxbyite?+
What minerals are found with roxbyite?+
What kind of rock does roxbyite form in?+
What is roxbyite used for?+
Find roxbyite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
