Middendorfite is a rare lead manganese silicate primarily found in the Långban mining district of Sweden. It typically occurs as small, bright orange fibrous masses or coatings within metamorphic manganese ores.
Is this middendorfite?
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 middendorfite with a known reference. Middendorfite sits at Mohs 3-3.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: yellowish.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: dark orange.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: lamellar, radial, tabular.
Often confused with
Middendorfite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Hancockite is the harder of the two (Mohs 6-7 vs. 3-3.5); streak differs, so Middendorfite leaves yellowish, Hancockite leaves grayish white.
How to tell apart: Kentrolite is the harder of the two (Mohs 5 vs. 3-3.5).
Often found alongside middendorfite
Minerals reported to co-occur with middendorfite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- K₃Na₂Mn₅Si₁₂(O,OH)₃₆·2H₂O
- Mohs hardness
- 3-3.5
- Density
- 2.60 g/cm³
- Colors
- Dark orange
- Streak
- Yellowish
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Lamellar, radial, tabular
- Cleavage
- Perfect {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A late hydrothermal mineral in a hyperperalkaline pegmatite
Where rockhounds find middendorfite
Classic worldwide localities
- Hilairite pegmatite, level +252 m, Kirovsky Mine, Mount Kukisvumchorr, Khibiny alkaline pluton, Kola Peninsula, Russia
Field-hunting tip
Where it forms: A late hydrothermal mineral in a hyperperalkaline pegmatite. If you start seeing microcline, sodalite, cancrisilite in float, you are in the right ground. Typical habit: lamellar, radial, tabular. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify middendorfite?+
Where is middendorfite found?+
What rocks look like middendorfite?+
What minerals are found with middendorfite?+
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Find middendorfite on the map
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