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 — Hjalmarite leaves white, Hornblende leaves grayish-white.

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

Compare →

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 — that is 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

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