Tegengrenite is a rare manganese-magnesium oxide belonging to the spinel group. It is primarily found as tiny, metallic, black grains within manganese-rich metamorphic rocks, most notably at the famous Långban locality in Sweden.

Hardness

Mohs

Luster

Metallic

Streak

Black

Transparency

Opaque

mineralrareSpinel Group family

Tegengrenite

Hardness: 6
Luster: Metallic
Streak: Black
Transparency: Opaque

Is this tegengrenite?

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 tegengrenite with a known reference. Tegengrenite sits at Mohs 6, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Tegengrenite leaves a black streak.
3
Read the luster
Hold the specimen under a strong light. Tegengrenite typically shows a metallic luster.
4
Match the color range
Compare against the expected color range: black.
5
Look at form & habit
Crystal system: cubic. Typical habit: anhedral grains.

Often confused with

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

How to tell apart: Streak differs, so Tegengrenite leaves black, Hausmannite leaves brownish-red; luster reads metallic on Tegengrenite and submetallic on Hausmannite.

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Often found alongside tegengrenite

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

All properties

Chemical formula: Mg(Mn,Sb)₂O₄
Mohs hardness: 6
Density: 4.67 g/cm³
Colors: Black
Streak: Black
Luster: Metallic
Transparency: Opaque
Crystal system: Cubic
Crystal habit: Anhedral Grains
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Metamorphosed Manganese Ore Deposits

Where rockhounds find tegengrenite

Classic worldwide localities

Långban, Sweden

Field-hunting tip

Look in metamorphosed manganese ore deposits country, the host setting where tegengrenite typically forms. If you start seeing hausmannite, magnetite, dolomite in float, you are in the right ground. Field specimens usually show a anhedral grains habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify tegengrenite?+

Mohs hardness is 6. It typically shows a metallic luster. The streak is black. Common colors include black.

Where is tegengrenite found?+

Notable localities include Långban, Sweden.

What rocks look like tegengrenite?+

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

What minerals are found with tegengrenite?+

Tegengrenite commonly co-occurs with Hausmannite, Magnetite, Dolomite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does tegengrenite form in?+

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

What is tegengrenite used for?+

Tegengrenite is used in collector.

Find tegengrenite on the map

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