Umbite is a rare potassium zirconium silicate mineral primarily found in the hyperalkaline complexes of the Kola Peninsula in Russia. It typically occurs as small, colorless prismatic crystals or radiating clusters within pegmatitic cavities, often associated with other exotic zirconium-bearing silicates.
Is this umbite?
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 umbite with a known reference. Umbite sits at Mohs ~4.5, 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: colorless, yellowish white.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: prismatic crystals, radial aggregates.
Often confused with
Umbite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Luster reads vitreous on Umbite and silky, vitreous to waxy or dull on Elpidite.
How to tell apart: Catapleiite is the harder of the two (Mohs 5.5-6 vs. ~4.5); luster reads vitreous on Umbite and weakly vitreous or dull on Catapleiite.
Often found alongside umbite
Minerals reported to co-occur with umbite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- K₂ZrSi₃O₉·H₂O
- Mohs hardness
- ~4.5
- Density
- 2.79 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Semitransparent
- Crystal system
- Orthorhombic
- Crystal habit
- Prismatic crystals, radial aggregates
- Cleavage
- On {010}, perfect, micaceous; {100}, less perfect
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In pegmatite in a differentiated alkalic massif
Where rockhounds find umbite
Classic worldwide localities
- In the valley of the Vuonnemiok River, Khibiny massif, Kola Peninsula, Russia (type locality)
Field-hunting tip
Where it forms: In pegmatite in a differentiated alkalic massif. If you start seeing kostylevite, wadeite, eudialyte in float, you are in the right ground. Typical habit: prismatic crystals, radial aggregates. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify umbite?+
Where is umbite found?+
What rocks look like umbite?+
What minerals are found with umbite?+
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Find umbite on the map
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