Ferdowsiite is an extremely rare silver-antimony-telluride sulfide mineral first discovered in the Kuh-e-Shah region of Iran. It typically occurs as microscopic anhedral grains associated with other sulfide minerals in epithermal vein deposits. Due to its extreme rarity, it is primarily of interest to advanced professional mineralogists and specialized systematic collectors.

Hardness

Mohs

Luster

Metallic

Streak

Black

Transparency

Opaque

mineralrare

Ferdowsiite

Hardness: 2
Luster: Metallic
Streak: Black
Transparency: Opaque

No image

Is this ferdowsiite?

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

Often confused with

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

mineral

Tetrahedrite

Mohs 3-4

How to tell apart: Tetrahedrite is the harder of the two (Mohs 3-4 vs. 2).

How to tell apart: Streak differs — Ferdowsiite leaves black, Stibnite leaves lead-gray.

Often found alongside ferdowsiite

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

All properties

Chemical formula: AgSb₂Te₂S₄
Mohs hardness: 2
Density: 4.96 g/cm³
Colors: Gray White
Streak: Black
Luster: Metallic
Transparency: Opaque
Crystal system: Triclinic
Crystal habit: Anhedral Grains
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Epithermal Quartz Veins
Typical price: n/a

Where rockhounds find ferdowsiite

Classic worldwide localities

Kuh-e-Shah, Iran

Field-hunting tip

Look in epithermal quartz veins country — that is the host setting where ferdowsiite typically forms. If you start seeing quartz, pyrite, stibnite in float, you are in the right ground. Field specimens usually show a anhedral grains habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify ferdowsiite?+

Mohs hardness is 2. It typically shows a metallic luster. The streak is black. Common colors include gray, white.

Where is ferdowsiite found?+

Notable localities include Kuh-e-Shah, Iran.

How much is ferdowsiite worth?+

Typical asking prices fall in the range of n/a. Quality, size, and provenance can move individual specimens well outside that range.

Is ferdowsiite safe to handle?+

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

What rocks look like ferdowsiite?+

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

What minerals are found with ferdowsiite?+

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

What kind of rock does ferdowsiite form in?+

Ferdowsiite typically forms in epithermal quartz veins. Working float back to the host body is the standard way to chase a fresh occurrence.

What is ferdowsiite used for?+

Ferdowsiite is used in collector.

Find ferdowsiite on the map

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