Elpidite is a rare sodium zirconium silicate commonly found as delicate, needle-like prismatic crystals or in fibrous, radiating aggregates. It is most frequently encountered by collectors in high-alkaline environments like Mont Saint-Hilaire or the pegmatites of Greenland. Collectors should look for its distinctive acicular habit often contrasting against dark host minerals.
Is this elpidite?
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 elpidite with a known reference. Elpidite sits at Mohs 5.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Elpidite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Elpidite typically shows a vitreous to pearly luster.
- 4Match the color rangeCompare against the expected color range: white, colorless, gray, pale yellow, pale pink.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: acicular or prismatic crystals, radiating fibrous masses.
Often confused with
Elpidite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Luster reads vitreous to pearly on Elpidite and vitreous on Natrolite.
How to tell apart: Luster reads vitreous to pearly on Elpidite and vitreous to silky on Pectolite.
How to tell apart: Luster reads vitreous to pearly on Elpidite and vitreous on Eudialyte.
Often found alongside elpidite
Minerals reported to co-occur with elpidite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Na₂ZrSi₆O₁₅·3H₂O
- Mohs hardness
- 5.5
- Density
- 2.58 g/cm³
- Streak
- White
- Luster
- Vitreous to Pearly
- Transparency
- Transparent
- Crystal system
- Orthorhombic
- Crystal habit
- Acicular or Prismatic Crystals, Radiating Fibrous Masses
- Cleavage
- Perfect On {110}
- Rarity
- Uncommon
- Uses
- Collector, Scientific Research
- Host rock
- Agpaitic Pegmatites and Alkaline Igneous Complexes
- Typical price
- $20-150 thumbnail to cabinet specimen
Where rockhounds find elpidite
Classic worldwide localities
- Narsarsuk, Greenland
- Mont Saint-Hilaire, Quebec, Canada
- Kola Peninsula, Russia
- Lovozero Massif, Russia
Field-hunting tip
Look in agpaitic pegmatites and alkaline igneous complexes country — that is the host setting where elpidite typically forms. If you start seeing eudialyte, aegirine, microcline in float, you are in the right ground. Field specimens usually show a acicular or prismatic crystals, radiating fibrous masses habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find elpidite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
