Demagistrisite is an exceptionally rare member of the garnet group discovered in the manganese mines of the Aosta Valley. It typically occurs as small, dark, anhedral grains embedded within manganese-rich silicate rocks and is primarily of interest to advanced mineralogists and systematic collectors.

Hardness

6.5-7

Mohs

Luster

Vitreous

Streak

White

Transparency

Opaque

mineralrareGarnet Group family

Demagistrisite

Hardness: 6.5-7
Luster: Vitreous
Streak: White
Transparency: Opaque

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Is this demagistrisite?

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 demagistrisite with a known reference. Demagistrisite sits at Mohs 6.5-7 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Demagistrisite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Demagistrisite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: dark brown, black.
5
Look at form & habit
Crystal system: cubic. Typical habit: anhedral grains.

Often confused with

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

How to tell apart: Streak differs — Demagistrisite leaves white, Braunite leaves black; luster reads vitreous on Demagistrisite and submetallic on Braunite.

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Often found alongside demagistrisite

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

All properties

Chemical formula: Na₂Mn₄Si₄O₁₂
Mohs hardness: 6.5-7
Density: 4.1 g/cm³
Colors: Dark Brown Black
Streak: White
Luster: Vitreous
Transparency: Opaque
Crystal system: Cubic
Crystal habit: Anhedral Grains
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Metamorphic Manganese-rich Rocks
Typical price: n/a

Where rockhounds find demagistrisite

Classic worldwide localities

St. Marcel, Aosta Valley, Italy

Field-hunting tip

Look in metamorphic manganese-rich rocks country — that is the host setting where demagistrisite typically forms. If you start seeing braunite, quartz, hematite 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 demagistrisite?+

Mohs hardness is 6.5-7. It typically shows a vitreous luster. The streak is white. Common colors include dark brown, black.

Where is demagistrisite found?+

Notable localities include St. Marcel, Aosta Valley, Italy.

How much is demagistrisite worth?+

Typical asking prices fall in the range of n/a. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like demagistrisite?+

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

What minerals are found with demagistrisite?+

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

What kind of rock does demagistrisite form in?+

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

What is demagistrisite used for?+

Demagistrisite is used in collector.

Find demagistrisite on the map

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