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

mineralrare

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, 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.