Caswellsilverite is an extremely rare sulfide mineral found almost exclusively in enstatite achondrite meteorites. It typically occurs as microscopic inclusions or small anhedral grains associated with other sulfides and pyroxenes. Due to its extraterrestrial origin and scarcity, it is highly sought after by meteorite collectors.

Hardness

1-2

Mohs

Luster

Metallic

Streak

Black

Transparency

Opaque

mineralrare

Caswellsilverite

Hardness: 1-2
Luster: Metallic
Streak: Black
Transparency: Opaque

Is this caswellsilverite?

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 caswellsilverite with a known reference. Caswellsilverite sits at Mohs 1-2, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: black.
3
Read the luster
Hold the specimen under a strong light. Luster: metallic.
4
Match the color range
Compare against the expected color range: yellow gray.
5
Look at form & habit
Crystal system: trigonal. Typical habit: anhedral grains.

Often confused with

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

mineral

Troilite

Mohs 3.5-4.5

How to tell apart: Troilite is the harder of the two (Mohs 3.5-4.5 vs. 1-2); streak differs, so Caswellsilverite leaves black, Troilite leaves dark grayish brown.

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Often found alongside caswellsilverite

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

All properties

Chemical formula: NaCrS₂
Mohs hardness: 1-2
Density: 3.21 g/cm³
Colors: Yellow gray
Streak: Black
Luster: Metallic
Transparency: Opaque
Crystal system: Trigonal
Crystal habit: Anhedral grains
Cleavage: Perfect
Rarity: Rare
Uses: Collector
Host rock: As inclusions in enstatite crystals and in the brecciated matrix of a meteorite (Norton County meteorite); between coarse pyroxene grains in chondrules in a meteorite (Qingzhen meteorite)

Where rockhounds find caswellsilverite

Classic worldwide localities

In the Norton County enstatite achondrite and the Qingzhen enstatite chondrite meteorites (type locality)

Field-hunting tip

Where it forms: As inclusions in enstatite crystals and in the brecciated matrix of a meteorite (Norton County meteorite); between coarse pyroxene grains in chondrules in a meteorite (Qingzhen meteorite). If you start seeing enstatite, cronusite, daubréelite in float, you are in the right ground. Typical habit: anhedral grains. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify caswellsilverite?+

Mohs hardness is 1-2. Luster: metallic. The streak is black. Common colors include yellow gray.

Where is caswellsilverite found?+

Notable localities include In the Norton County enstatite achondrite and the Qingzhen enstatite chondrite meteorites (type locality).

What rocks look like caswellsilverite?+

Caswellsilverite is most often confused with Troilite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with caswellsilverite?+

Caswellsilverite commonly co-occurs with Enstatite, Cronusite, Daubréelite, Titanoan troilite, Ferromagnesian alabandite, Oldhamite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does caswellsilverite form in?+

Where it forms: As inclusions in enstatite crystals and in the brecciated matrix of a meteorite (Norton County meteorite); between coarse pyroxene grains in chondrules in a meteorite (Qingzhen meteorite). Working float back to the host body is the standard way to chase a fresh occurrence.

What is caswellsilverite used for?+

Caswellsilverite is used in collector.

Find caswellsilverite on the map

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