Hjalmarite is a rare member of the amphibole group, typically found in manganese-rich metamorphic deposits. It is best identified by its distinct brownish color and typical prismatic habit, usually occurring within skarn environments.

Hardness

5.5-6

Mohs

Luster

Vitreous

Streak

White

Transparency

Translucent

mineralrareAmphibole Supergroup family

Hjalmarite

Hardness: 5.5-6
Luster: Vitreous
Streak: White
Transparency: Translucent

No image

Is this hjalmarite?

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 hjalmarite with a known reference. Hjalmarite sits at Mohs 5.5-6, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Hjalmarite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Hjalmarite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: brown, yellowish-brown.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: prismatic crystals.

Often confused with

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

mineral

Hornblende

Mohs 5-6

How to tell apart: Streak differs, so Hjalmarite leaves white, Hornblende leaves grayish-white.

How to tell apart: Luster reads vitreous on Hjalmarite and vitreous to silky on Actinolite.

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Often found alongside hjalmarite

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

All properties

Chemical formula: Na(NaMg₃AlMg)(Si₆Al₂)O₂₂(OH)₂
Mohs hardness: 5.5-6
Density: 3.32 g/cm³
Colors: Brown Yellowish-brown
Streak: White
Luster: Vitreous
Transparency: Translucent
Crystal system: Monoclinic
Crystal habit: Prismatic Crystals
Cleavage: Perfect Prismatic
Rarity: Rare
Uses: Collector
Host rock: Metamorphic Rocks
Typical price: $20-100 per specimen

Where rockhounds find hjalmarite

Classic worldwide localities

Hjalmar, Sweden
Langban, Sweden

Field-hunting tip

Look in metamorphic rocks country, the host setting where hjalmarite typically forms. If you start seeing calcite, magnetite, phlogopite in float, you are in the right ground. Field specimens usually show a prismatic crystals habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify hjalmarite?+

Mohs hardness is 5.5-6. It typically shows a vitreous luster. The streak is white. Common colors include brown, yellowish-brown.

Where is hjalmarite found?+

Notable localities include Hjalmar, Sweden; Langban, Sweden.

How much is hjalmarite worth?+

Typical asking prices fall in the range of $20-100 per specimen. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like hjalmarite?+

Hjalmarite is most often confused with Hornblende, Tremolite, Actinolite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with hjalmarite?+

Hjalmarite commonly co-occurs with Calcite, Magnetite, Phlogopite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does hjalmarite form in?+

Hjalmarite typically forms in metamorphic rocks. Working float back to the host body is the standard way to chase a fresh occurrence.

What is hjalmarite used for?+

Hjalmarite is used in collector.

Find hjalmarite on the map

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