Manganilvaite is a rare manganese-rich member of the ilvaite group, typically occurring in dark, submetallic prismatic crystals. It is most frequently found in skarn deposits where limestone has been altered by hydrothermal activity and igneous intrusions. Collectors identify it by its specific habit and association with other contact metamorphic minerals, often requiring chemical testing to distinguish from standard ilvaite.
Is this manganilvaite?
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 manganilvaite with a known reference. Manganilvaite sits at Mohs 5.5-6, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: black to brownish black.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: black.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: pyramidal, striated.
Often confused with
Manganilvaite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Luster reads vitreous on Manganilvaite and submetallic on Ilvaite.
How to tell apart: Streak differs, so Manganilvaite leaves black to brownish black, Allanite leaves gray; luster reads vitreous on Manganilvaite and submetallic on Allanite.
Often found alongside manganilvaite
Minerals reported to co-occur with manganilvaite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaFe²⁺Fe³⁺Mn²⁺(Si₂O₇)O(OH)
- Mohs hardness
- 5.5-6
- Density
- 3.92 g/cm³
- Colors
- Streak
- Black to brownish black
- Luster
- Vitreous
- Transparency
- Opaque to semitransparent
- Crystal system
- Monoclinic
- Crystal habit
- Pyramidal, striated
- Cleavage
- Distinct on {100}
- Rarity
- Rare
- Uses
- Collector, Scientific research
- Host rock
- From the retrograde, hydrothermal alteration of manganiferous minerals in Pb-Zn-(Mn) contact metamorphic rocks (skarns)
Where rockhounds find manganilvaite
Classic worldwide localities
- Ossikovo and Mogilata deposits, Madan ore district and from the Govedarnika deposit, Laki district, central Rhodope Mountains, Bulgaria
Field-hunting tip
Where it forms: From the retrograde, hydrothermal alteration of manganiferous minerals in Pb-Zn-(Mn) contact metamorphic rocks (skarns). If you start seeing bustamite, hedenbergite-johannsenite, manganoan ferro-actinolite in float, you are in the right ground. Typical habit: pyramidal, striated. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify manganilvaite?+
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What rocks look like manganilvaite?+
What minerals are found with manganilvaite?+
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Find manganilvaite on the map
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