Achávalite is a rare iron selenide mineral that typically forms as metallic, bronze-colored grains within hydrothermal veins. Collectors most often find it in argentiferous or selenide-bearing mineral deposits where it is usually associated with other rare sulfide and selenide species.

Hardness

3.5-4

Mohs

Luster

Metallic

Streak

Black

Transparency

Opaque

mineralrare

Achávalite

Hardness: 3.5-4
Luster: Metallic
Streak: Black
Transparency: Opaque

Is this achávalite?

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

Often confused with

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

mineral

Pyrrhotite

Mohs 3.5-4.5

How to tell apart: Streak differs, so Achávalite leaves black, Pyrrhotite leaves dark grey to black.

Often found alongside achávalite

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

All properties

Chemical formula: FeSe
Mohs hardness: 3.5-4
Density: 6.6 g/cm³
Colors: Bronze Reddish-brown
Streak: Black
Luster: Metallic
Transparency: Opaque
Crystal system: Hexagonal
Crystal habit: Massive, Anhedral Grains
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Hydrothermal Veins
Typical price: $50-300 per specimen

Where rockhounds find achávalite

Classic worldwide localities

Cacheuta, Argentina
Krushev Dol, Bulgaria

Field-hunting tip

Look in hydrothermal veins country, the host setting where achávalite typically forms. If you start seeing calcite, pyrite, siderite in float, you are in the right ground. Field specimens usually show a massive, anhedral grains habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify achávalite?+

Mohs hardness is 3.5-4. It typically shows a metallic luster. The streak is black. Common colors include bronze, reddish-brown.

Where is achávalite found?+

Notable localities include Cacheuta, Argentina; Krushev Dol, Bulgaria.

How much is achávalite worth?+

Typical asking prices fall in the range of $50-300 per specimen. Quality, size, and provenance can move individual specimens well outside that range.

Is achávalite safe to handle?+

It contains toxic constituents. Contains selenium, which is toxic if inhaled as dust or ingested. Handle with care and wash hands thoroughly after handling. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like achávalite?+

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

What minerals are found with achávalite?+

Achávalite commonly co-occurs with Calcite, Pyrite, Siderite, Umbertovidalite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does achávalite form in?+

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

What is achávalite used for?+

Achávalite is used in collector.

Find achávalite on the map

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