Matlockite is a rare lead halide mineral known for its high refractive index and excellent adamantine luster. It typically forms thin, transparent, tabular crystals in the oxidation zones of lead-bearing ore deposits.

Hardness

2.5-3

Mohs

Luster

Adamantine, pearly on {001}

Streak

White

Transparency

Transparent

mineralrare

Matlockite

Hardness: 2.5-3
Luster: Adamantine, pearly on {001}
Streak: White
Transparency: Transparent

Is this matlockite?

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 matlockite with a known reference. Matlockite sits at Mohs 2.5-3, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: white.
3
Read the luster
Hold the specimen under a strong light. Luster: adamantine, pearly on {001}.
4
Match the color range
Compare against the expected color range: brownish yellow, colorless, green yellow, dark yellow brown.
5
Look at form & habit
Crystal system: tetragonal. Typical habit: crystalline, tabular.

Often confused with

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

Often found alongside matlockite

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

All properties

Chemical formula: PbFCl
Mohs hardness: 2.5-3
Density: 7.12 g/cm³
Colors: Brownish yellow Colorless Green yellowDark yellow brown
Streak: White
Luster: Adamantine, pearly on {001}
Transparency: Transparent
Crystal system: Tetragonal
Crystal habit: Crystalline, tabular
Cleavage: {001}, perfect
Rarity: Rare
Uses: Collector
Host rock: In the oxide zone of some lead-bearing mineral deposits

Where rockhounds find matlockite

Classic worldwide localities

Mammoth-St. Anthony mine, Tiger, Pinal Co., USA
Apache mine, Gila Co., USA
Mildren mine, Cabibi district, South Comobabi Mountains, Arizona, USA
Bage and Wallclose mines, about 2.5 km south of Matlock, Derbyshire, England
Slag, at Laurium, Greece
Slag, along Baratti Beach and one km north of Campiglia, Tuscany, Italy

Field-hunting tip

Where it forms: In the oxide zone of some lead-bearing mineral deposits. If you start seeing phosgenite, anglesite, cerussite in float, you are in the right ground. Typical habit: crystalline, tabular. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify matlockite?+

Mohs hardness is 2.5-3. Luster: adamantine, pearly on {001}. The streak is white. Common colors include brownish yellow, colorless, green yellow, dark yellow brown.

Where is matlockite found?+

Notable localities include Mammoth-St. Anthony mine, Tiger, Pinal Co., USA; Apache mine, Gila Co., USA; Mildren mine, Cabibi district, South Comobabi Mountains, Arizona, USA; Bage and Wallclose mines, about 2.5 km south of Matlock, Derbyshire, England; Slag, at Laurium, Greece.

Is matlockite safe to handle?+

Matlockite contains lead. Contains lead; avoid inhaling dust and wash hands thoroughly after handling. Keep specimens away from children and pets.

What rocks look like matlockite?+

Matlockite is most often confused with Phosgenite, Anglesite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with matlockite?+

Matlockite commonly co-occurs with Phosgenite, Anglesite, Cerussite, Galena, Sphalerite, Barite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does matlockite form in?+

Where it forms: In the oxide zone of some lead-bearing mineral deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

What is matlockite used for?+

Matlockite is used in collector.

Find matlockite on the map

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