Devilline is a striking secondary copper mineral that typically forms delicate, fan-shaped clusters of bright blue to greenish-blue platy crystals. It is most commonly found in the oxidation zones of sulfide ore deposits, often appearing as coatings on other copper minerals like malachite or azurite. Because of its fragile nature and solubility, it is highly prized by mineral collectors who appreciate its vivid color and unique crystal habits.

Hardness

2.5

Mohs

Luster

Vitreous, may be pearly on {001}

Streak

Pale green

Transparency

Transparent to translucent

mineraluncommon

Devilline

Also: Devillite, Herrengrundite

Hardness: 2.5
Luster: Vitreous, may be pearly on {001}
Streak: Pale green
Transparency: Transparent to translucent

Is this devilline?

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 devilline with a known reference. Devilline sits at Mohs 2.5, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: pale green.
3
Read the luster
Hold the specimen under a strong light. Luster: vitreous, may be pearly on {001}.
4
Match the color range
Compare against the expected color range: blue, blue green, blue white, white, dark green.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: platy, spherical, tabular.

Often confused with

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

mineral

Langite

Mohs 2.5-3

How to tell apart: Streak differs, so Devilline leaves pale green, Langite leaves greenish blue.

How to tell apart: Brochantite is the harder of the two (Mohs 3.5-4 vs. 2.5).

Compare →

Often found alongside devilline

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

All properties

Chemical formula: CaCu₄(SO₄)₂(OH)₆·3H₂O
Mohs hardness: 2.5
Density: 3.13 g/cm³
Colors: Blue Blue greenBlue whiteWhite Dark green
Streak: Pale green
Luster: Vitreous, may be pearly on {001}
Transparency: Transparent to translucent
Crystal system: Monoclinic
Crystal habit: Platy, spherical, tabular
Cleavage: On {001}, perfect; on {110}, {101}, {101}, distinct
Rarity: Uncommon
Uses: Collector
Host rock: An uncommon secondary mineral in the oxidized portions of copper sulfide deposits; may be of post-mining origin in dumps and on timbers

Where rockhounds find devilline

Classic worldwide localities

Ecton mine, Montgomery Co., Pennsylvania, USA
Sterling Hill, Ogdensburg, New Jersey, USA
Majuba Hill, Pershing Co., Nevada, USA
Trixie mine, Tintic district, Juab Co., Utah, USA
Cornwall, at several mines around St. Just, St. Hilary, and Gwinear, England
Wheal Friendship, Mary Tavy, Devon, England

Field-hunting tip

Where it forms: An uncommon secondary mineral in the oxidized portions of copper sulfide deposits; may be of post-mining origin in dumps and on timbers. If you start seeing langite, antlerite, brochantite in float, you are in the right ground. Typical habit: platy, spherical, tabular. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify devilline?+

Mohs hardness is 2.5. Luster: vitreous, may be pearly on {001}. The streak is pale green. Common colors include blue, blue green, blue white, white.

Where is devilline found?+

Notable localities include Ecton mine, Montgomery Co., Pennsylvania, USA; Sterling Hill, Ogdensburg, New Jersey, USA; Majuba Hill, Pershing Co., Nevada, USA; Trixie mine, Tintic district, Juab Co., Utah, USA; Cornwall, at several mines around St. Just, St. Hilary, and Gwinear, England.

Is devilline safe to handle?+

Devilline contains copper. Contains copper; wash hands after handling to avoid ingestion or skin irritation from dust.

What rocks look like devilline?+

Devilline is most often confused with Langite, Posnjakite, Brochantite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with devilline?+

Devilline commonly co-occurs with Langite, Antlerite, Brochantite, Posnjakite, Linarite, Malachite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does devilline form in?+

Where it forms: An uncommon secondary mineral in the oxidized portions of copper sulfide deposits; may be of post-mining origin in dumps and on timbers. Working float back to the host body is the standard way to chase a fresh occurrence.

What is devilline used for?+

Devilline is used in collector.

Find devilline on the map

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