Magnesiodumortierite is a rare magnesium-dominant analogue of the standard dumortierite species, characterized by its vibrant blue to violet coloration. It typically occurs as fibrous aggregates or massive veins within aluminum-rich metamorphic environments such as pelitic schists and gneisses.
Is this magnesiodumortierite?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch magnesiodumortierite with a known reference. Magnesiodumortierite sits at Mohs 7.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: pinkish red, red.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: disseminated.
Often confused with
Magnesiodumortierite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside magnesiodumortierite
Minerals reported to co-occur with magnesiodumortierite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- MgAl₆BSi₃O₁₇(OH)
- Mohs hardness
- 7.5
- Density
- 3.22 g/cm³
- Colors
- Pinkish redRed
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Orthorhombic
- Crystal habit
- Disseminated
- Cleavage
- Poor on {001}
- Rarity
- Rare
- Uses
- Collector, Lapidary
- Host rock
- In pyrope megablasts which occur in coesite bearing quartz-phengite-kyanite schists
Where rockhounds find magnesiodumortierite
Classic worldwide localities
- Dor-Maira massif, western Alps, Italy (type locality)
Field-hunting tip
Where it forms: In pyrope megablasts which occur in coesite bearing quartz-phengite-kyanite schists. If you start seeing quartz, kyanite, garnet in float, you are in the right ground. Typical habit: disseminated. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify magnesiodumortierite?+
Where is magnesiodumortierite found?+
What rocks look like magnesiodumortierite?+
What minerals are found with magnesiodumortierite?+
What kind of rock does magnesiodumortierite form in?+
What is magnesiodumortierite used for?+
Find magnesiodumortierite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
