Hydrodelhayelite is an extremely rare phyllosilicate mineral typically found in alkaline igneous rocks. It is most easily identified by its characteristic pearly luster and platy habit, though it is usually only found as microscopic inclusions or small aggregates within host rocks.
Is this hydrodelhayelite?
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 hydrodelhayelite with a known reference. Hydrodelhayelite sits at Mohs 3 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Hydrodelhayelite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Hydrodelhayelite typically shows a pearly luster.
- 4Match the color rangeCompare against the expected color range: colorless, white.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: platy or micaceous aggregates.
Often confused with
Hydrodelhayelite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside hydrodelhayelite
Minerals reported to co-occur with hydrodelhayelite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (K,Na,Ca)₈(Si,Al)₁₈O₃₀(OH,F)₄·6H₂O
- Mohs hardness
- 3
- Density
- 2.33 g/cm³
- Streak
- White
- Luster
- Pearly
- Transparency
- Translucent
- Crystal system
- Orthorhombic
- Crystal habit
- Platy or Micaceous Aggregates
- Cleavage
- Perfect Basal
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Alkaline Volcanic Rocks
- Typical price
- not applicable for market
Where rockhounds find hydrodelhayelite
Classic worldwide localities
- Mount Nyiragongo, Democratic Republic of the Congo
- Khibiny Massif, Russia
Field-hunting tip
Look in alkaline volcanic rocks country — that is the host setting where hydrodelhayelite typically forms. If you start seeing nepheline, phlogopite, cancrinite 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
How do you identify hydrodelhayelite?+
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How much is hydrodelhayelite worth?+
What rocks look like hydrodelhayelite?+
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Find hydrodelhayelite on the map
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