Hennomartinite is a very rare manganese-strontium silicate that belongs to the pumpellyite group. It is primarily found in the metamorphosed manganese ore deposits of the Jacobsberg mine in Sweden, typically occurring as small granular masses.

Hardness

6-6.5

Mohs

Luster

Vitreous

Streak

White

Transparency

Translucent

mineralrarePumpellyite Group family

Hennomartinite

Hardness: 6-6.5
Luster: Vitreous
Streak: White
Transparency: Translucent

Is this hennomartinite?

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 hennomartinite with a known reference. Hennomartinite sits at Mohs 6-6.5 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Hennomartinite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Hennomartinite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: pink, brown.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: granular to massive.

Often found alongside hennomartinite

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

All properties

Chemical formula: SrMn³⁺₂Al(Si₂O₇)(SiO₄)O(OH)
Mohs hardness: 6-6.5
Density: 3.32 g/cm³
Colors: Pink Brown
Streak: White
Luster: Vitreous
Transparency: Translucent
Crystal system: Monoclinic
Crystal habit: Granular to Massive
Cleavage: Poor
Rarity: Rare
Uses: Collector
Host rock: Manganese Ore Deposits
Typical price: $50-300 per specimen depending on size and provenance

Where rockhounds find hennomartinite

Classic worldwide localities

Hennomartin, Jacobsberg Mine, Nordmark, Sweden

Field-hunting tip

Look in manganese ore deposits country — that is the host setting where hennomartinite typically forms. If you start seeing hausmannite, baryte, calcite in float, you are in the right ground. Field specimens usually show a granular to massive habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify hennomartinite?+

Mohs hardness is 6-6.5. It typically shows a vitreous luster. The streak is white. Common colors include pink, brown.

Where is hennomartinite found?+

Notable localities include Hennomartin, Jacobsberg Mine, Nordmark, Sweden.

How much is hennomartinite worth?+

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

What minerals are found with hennomartinite?+

Hennomartinite commonly co-occurs with Hausmannite, Baryte, Calcite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does hennomartinite form in?+

Hennomartinite typically forms in manganese ore deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

What is hennomartinite used for?+

Hennomartinite is used in collector.

Find hennomartinite on the map

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