Ekplexite is a rare niobium molybdenum magnesium hydroxide, typically iron black. It was approved as a distinct mineral species in 2011. It was first described from Mt. Kaskasnyunchorr, Khibiny alkaline complex, Kola Peninsula, Russia.
Is this ekplexite?
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 ekplexite with a known reference. Ekplexite sits at Mohs 1, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Ekplexite leaves a black streak.
- 3Read the lusterHold the specimen under a strong light. Ekplexite typically shows a metallic luster.
- 4Match the color rangeCompare against the expected color range: iron black.
- 5Look at form & habitCrystal system: hexagonal. Typical habit: platy or micaceous aggregates.
Often confused with
Ekplexite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Ekplexite leaves black, Molybdenite leaves greenish-gray.
How to tell apart: Bismuthinite is the harder of the two (Mohs 2 vs. 1); streak differs, so Ekplexite leaves black, Bismuthinite leaves lead-gray.
Often found alongside ekplexite
Minerals reported to co-occur with ekplexite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Nb,Mo)S₂·(Mg₁₋ₓAlₓ)(OH)₂₊ₓ
- Mohs hardness
- 1
- Density
- 3.63 g/cm³
- Colors
- Streak
- Black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Hexagonal
- Crystal habit
- Platy or Micaceous Aggregates
- Cleavage
- Perfect On {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Alkaline Pegmatites
Where rockhounds find ekplexite
Classic worldwide localities
- Khibiny Massif, Russia
- Lovozero Massif, Russia
Field-hunting tip
Look in alkaline pegmatites country, the host setting where ekplexite typically forms. If you start seeing aegirine, nepheline, microcline in float, you are in the right ground. Field specimens usually show a platy or micaceous aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find ekplexite on the map
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