Byströmite is a rare magnesium antimonate mineral that typically forms as small, prismatic, transparent yellow crystals. It is most commonly found in association with antimony ore bodies and is a prized target for advanced mineral collectors.

Hardness

Mohs

Luster

Adamantine

Streak

Pale gray

Transparency

Transparent to translucent

mineralrare

Byströmite

Hardness: ~7
Luster: Adamantine
Streak: Pale gray
Transparency: Transparent to translucent

Is this byströmite?

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 byströmite with a known reference. Byströmite sits at Mohs ~7, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: pale gray.
3
Read the luster
Hold the specimen under a strong light. Luster: adamantine.
4
Match the color range
Compare against the expected color range: blue.
5
Look at form & habit
Crystal system: tetragonal. Typical habit: prismatic crystals.

Often confused with

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

Often found alongside byströmite

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

All properties

Chemical formula: MgSb₂O₆
Mohs hardness: ~7
Density: 5.5 g/cm³
Colors: Blue
Streak: Pale gray
Luster: Adamantine
Transparency: Transparent to translucent
Crystal system: Tetragonal
Crystal habit: Prismatic crystals
Cleavage: Distinct on {110}
Rarity: Rare
Uses: Collector
Host rock: In quartz veins in an oxidized antimony deposit

Where rockhounds find byströmite

Classic worldwide localities

La Fortuna and San Jose mines, El Antimonio, 27 km southwest of Agua Prieta, Sonora, Mexico

Field-hunting tip

Where it forms: In quartz veins in an oxidized antimony deposit. If you start seeing stibiconite, quartz in float, you are in the right ground. Typical habit: prismatic crystals. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify byströmite?+

Mohs hardness is ~7. Luster: adamantine. The streak is pale gray. Common colors include blue.

Where is byströmite found?+

Notable localities include La Fortuna and San Jose mines, El Antimonio, 27 km southwest of Agua Prieta, Sonora, Mexico.

Is byströmite safe to handle?+

Byströmite contains antimony. Wash your hands afterwards, never grind or breathe the dust, and store it apart from specimens you handle often.

What rocks look like byströmite?+

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

What minerals are found with byströmite?+

Byströmite commonly co-occurs with Stibiconite, Quartz. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does byströmite form in?+

Where it forms: In quartz veins in an oxidized antimony deposit. Working float back to the host body is the standard way to chase a fresh occurrence.

What is byströmite used for?+

Byströmite is used in collector.

Find byströmite on the map

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