Criddleite is an extremely rare sulfosalt mineral found in gold-bearing hydrothermal deposits. It is typically identified through microscopic examination of polished sections, appearing as small, grey metallic grains intergrown with other minerals like aurostibite and stibnite.

Hardness

3-3.5

Mohs

Luster

Metallic

Streak

Black

Transparency

Opaque

mineralrare

Criddleite

Hardness: 3-3.5
Luster: Metallic
Streak: Black
Transparency: Opaque

Is this criddleite?

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 criddleite with a known reference. Criddleite sits at Mohs 3-3.5 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Criddleite leaves a black streak.
3
Read the luster
Hold the specimen under a strong light. Criddleite typically shows a metallic luster.
4
Match the color range
Compare against the expected color range: gray.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: anhedral grains and inclusions.

Often confused with

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

How to tell apart: Criddleite is noticeably harder (Mohs 3-3.5 vs. 2); streak differs — Criddleite leaves black, Stibnite leaves lead-gray.

How to tell apart: Gudmundite is the harder of the two (Mohs 6 vs. 3-3.5); streak differs — Criddleite leaves black, Gudmundite leaves dark gray to black.

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Often found alongside criddleite

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

All properties

Chemical formula: Ag₂Au₃Sb₁₀S₁₀
Mohs hardness: 3-3.5
Density: 8.7 g/cm³
Colors: Gray
Streak: Black
Luster: Metallic
Transparency: Opaque
Crystal system: Monoclinic
Crystal habit: Anhedral Grains and Inclusions
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Hydrothermal Gold Deposits
Typical price: $200-800+ depending on size and rarity of specimen

Where rockhounds find criddleite

Classic worldwide localities

Hemlo gold deposit, Ontario, Canada

Field-hunting tip

Look in hydrothermal gold deposits country — that is the host setting where criddleite typically forms. If you start seeing aurostibite, stibnite, pyrite in float, you are in the right ground. Field specimens usually show a anhedral grains and inclusions habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify criddleite?+

Mohs hardness is 3-3.5. It typically shows a metallic luster. The streak is black. Common colors include gray.

Where is criddleite found?+

Notable localities include Hemlo gold deposit, Ontario, Canada.

How much is criddleite worth?+

Typical asking prices fall in the range of $200-800+ depending on size and rarity of specimen. Quality, size, and provenance can move individual specimens well outside that range.

Is criddleite safe to handle?+

It contains toxic constituents. Contains silver, gold, antimony, and sulfur; handle with care to avoid ingestion or inhalation of dust. Wash hands thoroughly after handling. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like criddleite?+

Criddleite is most often confused with Aurostibite, Stibnite, Gudmundite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with criddleite?+

Criddleite commonly co-occurs with Aurostibite, Stibnite, Pyrite, Quartz, Gold. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does criddleite form in?+

Criddleite typically forms in hydrothermal gold deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

What is criddleite used for?+

Criddleite is used in collector.

Find criddleite on the map

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