Geocronite is a rare lead-arsenic sulfosalt often found in hydrothermal lead-zinc deposits. It typically presents as metallic lead-gray massive or granular masses, making it visually similar to galena but distinguishable by its specific chemical associations and rarity.

Hardness

2.5

Mohs

Luster

Metallic

Streak

Lead-gray

Transparency

Opaque

mineralrare

Geocronite

Hardness: 2.5
Luster: Metallic
Streak: Lead-gray
Transparency: Opaque

Is this geocronite?

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 geocronite with a known reference. Geocronite 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. Geocronite leaves a lead-gray streak.
3
Read the luster
Hold the specimen under a strong light. Geocronite typically shows a metallic luster.
4
Match the color range
Compare against the expected color range: lead-gray, grayish-blue.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: granular, massive, occasionally tabular crystals.

Often confused with

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

How to tell apart: Streak differs, so Geocronite leaves lead-gray, Bournonite leaves steel-gray.

How to tell apart: Streak differs, so Geocronite leaves lead-gray, Jamesonite leaves gray-black.

Compare →

Often found alongside geocronite

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

All properties

Chemical formula: Pb₁₄As₆S₂₃
Mohs hardness: 2.5
Density: 6.4-6.5 g/cm³
Colors: Lead-gray Grayish-blue
Streak: Lead-gray
Luster: Metallic
Transparency: Opaque
Crystal system: Monoclinic
Crystal habit: Granular, Massive, Occasionally Tabular Crystals
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Hydrothermal Sulfide Veins
Typical price: $20-150 thumbnail, $200+ cabinet specimen

Where rockhounds find geocronite

Classic worldwide localities

Sala, Sweden
Miny, Spain
Pribram, Czech Republic
Eureka, Nevada, USA

Field-hunting tip

Look in hydrothermal sulfide veins country, the host setting where geocronite typically forms. If you start seeing galena, sphalerite, pyrite in float, you are in the right ground. Field specimens usually show a granular, massive, occasionally tabular crystals habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify geocronite?+

Mohs hardness is 2.5. It typically shows a metallic luster. The streak is lead-gray. Common colors include lead-gray, grayish-blue.

Where is geocronite found?+

Notable localities include Sala, Sweden; Miny, Spain; Pribram, Czech Republic; Eureka, Nevada, USA.

How much is geocronite worth?+

Typical asking prices fall in the range of $20-150 thumbnail, $200+ cabinet specimen. Quality, size, and provenance can move individual specimens well outside that range.

Is geocronite safe to handle?+

It contains toxic constituents. Contains lead and arsenic; handle with care and wash hands thoroughly after handling. Do not ingest, inhale dust, or use for lapidary work without protective equipment. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like geocronite?+

Geocronite is most often confused with Galena, Bournonite, Jamesonite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with geocronite?+

Geocronite commonly co-occurs with Galena, Sphalerite, Pyrite, Arsenopyrite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does geocronite form in?+

Geocronite typically forms in hydrothermal sulfide veins. Working float back to the host body is the standard way to chase a fresh occurrence.

What is geocronite used for?+

Geocronite is used in collector.

Find geocronite on the map

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