Corkite is a rare phosphate-sulfate mineral that typically forms as a secondary mineral in the oxidized zones of lead-bearing ore deposits. It is most often found as small, yellowish-brown rhombohedral crystals or crusts coating other ores and is prized by micromount collectors.

Hardness

3.5-4

Mohs

Luster

Vitreous

Streak

Yellow

Transparency

Translucent

mineraluncommonBeudantite Group family

Corkite

Hardness: 3.5-4
Luster: Vitreous
Streak: Yellow
Transparency: Translucent

Is this corkite?

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 corkite with a known reference. Corkite sits at Mohs 3.5-4 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Corkite leaves a yellow streak.
3
Read the luster
Hold the specimen under a strong light. Corkite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: yellow, brown, greenish-brown, yellow-brown.
5
Look at form & habit
Crystal system: trigonal. Typical habit: rhombohedral crystals, pseudocubic, crusts, earthy aggregates.

Often confused with

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

How to tell apart: Luster reads vitreous on Corkite and earthy on Plumbojarosite.

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Often found alongside corkite

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

All properties

Chemical formula: PbFe₃(PO₄)(SO₄)(OH)₆
Mohs hardness: 3.5-4
Density: 4.2-4.3 g/cm³
Colors: Yellow Brown Greenish-brown Yellow-brown
Streak: Yellow
Luster: Vitreous
Transparency: Translucent
Crystal system: Trigonal
Crystal habit: Rhombohedral Crystals, Pseudocubic, Crusts, Earthy Aggregates
Cleavage: Poor
Rarity: Uncommon
Uses: Collector
Host rock: Oxidized Hydrothermal Lead-zinc Deposits
Typical price: $20-150 for micro to thumbnail specimens

Where rockhounds find corkite

Classic worldwide localities

Cork, Ireland
Glanmire, Ireland
Black Forest, Germany
Laurion, Greece

Field-hunting tip

Look in oxidized hydrothermal lead-zinc deposits country — that is the host setting where corkite typically forms. If you start seeing pyromorphite, limonite, goethite in float, you are in the right ground. Field specimens usually show a rhombohedral crystals, pseudocubic, crusts, earthy aggregates habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify corkite?+

Mohs hardness is 3.5-4. It typically shows a vitreous luster. The streak is yellow. Common colors include yellow, brown, greenish-brown, yellow-brown.

Where is corkite found?+

Notable localities include Cork, Ireland; Glanmire, Ireland; Black Forest, Germany; Laurion, Greece.

How much is corkite worth?+

Typical asking prices fall in the range of $20-150 for micro to thumbnail specimens. Quality, size, and provenance can move individual specimens well outside that range.

Is corkite safe to handle?+

It contains toxic constituents. Contains lead, which is toxic if ingested or inhaled as dust. Always wash hands thoroughly after handling specimens. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like corkite?+

Corkite is most often confused with Beudantite, Jarosite, Plumbojarosite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with corkite?+

Corkite commonly co-occurs with Pyromorphite, Limonite, Goethite, Cerussite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does corkite form in?+

Corkite typically forms in oxidized hydrothermal lead-zinc deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

What is corkite used for?+

Corkite is used in collector.

Find corkite on the map

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