Mcconnellite is a rare copper chromium oxide mineral that occurs as small, dark, metallic tabular crystals in oxidized zones of copper deposits. It is structurally related to the delafossite group and is primarily a curiosity for advanced mineralogists and systematic collectors. Specimens are typically microscopic to thumbnail-sized and are found in very limited localities worldwide.

Hardness

Mohs

Luster

Metallic

Streak

Black

Transparency

Opaque

mineralrarenull family

Mcconnellite

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

Is this mcconnellite?

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 mcconnellite with a known reference. Mcconnellite sits at Mohs 3 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Mcconnellite leaves a black streak.
3
Read the luster
Hold the specimen under a strong light. Mcconnellite 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: trigonal. Typical habit: tabular crystals.

Often confused with

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

mineral

Delafossite

Mohs 5.5

How to tell apart: Delafossite is the harder of the two (Mohs 5.5 vs. 3).

Compare →

Often found alongside mcconnellite

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

All properties

Chemical formula: CuCrO₂
Mohs hardness: 3
Density: 8.8 g/cm³
Colors: Dark Gray Black
Streak: Black
Luster: Metallic
Transparency: Opaque
Crystal system: Trigonal
Crystal habit: Tabular Crystals
Cleavage: Perfect
Rarity: Rare
Uses: Collector
Host rock: Oxidized Copper Deposits
Typical price: $50-300 per specimen depending on size and provenance

Where rockhounds find mcconnellite

Classic worldwide localities

Mohave County, Arizona, USA
Sierra Nevada, California, USA

Field-hunting tip

Look in oxidized copper deposits country — that is the host setting where mcconnellite typically forms. If you start seeing delafossite, chrysocolla, quartz in float, you are in the right ground. Field specimens usually show a tabular crystals habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify mcconnellite?+

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

Where is mcconnellite found?+

Notable localities include Mohave County, Arizona, USA; Sierra Nevada, California, USA.

How much is mcconnellite worth?+

Typical asking prices fall in the range of $50-300 per specimen depending on size and provenance. Quality, size, and provenance can move individual specimens well outside that range.

Is mcconnellite safe to handle?+

It contains toxic constituents. Contains chromium and copper; wash hands thoroughly after handling and avoid ingestion or inhalation of dust. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like mcconnellite?+

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

What minerals are found with mcconnellite?+

Mcconnellite commonly co-occurs with Delafossite, Chrysocolla, Quartz. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does mcconnellite form in?+

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

What is mcconnellite used for?+

Mcconnellite is used in collector.

Find mcconnellite on the map

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