Gaidonnayite is a rare zirconium silicate mineral primarily found in highly alkaline igneous environments. Collectors prize it for its sharp, well-formed tabular orthorhombic crystals, which are often found lining cavities in nepheline syenite pegmatites.
Is this gaidonnayite?
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 gaidonnayite with a known reference. Gaidonnayite sits at Mohs ~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: white, colorless, light lilac.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: tabular crystals, radiating clusters, drusy coatings.
Often confused with
Gaidonnayite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside gaidonnayite
Minerals reported to co-occur with gaidonnayite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Na₂ZrSi₃O₉·2H₂O
- Mohs hardness
- ~5
- Density
- 2.67 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent to opaque
- Crystal system
- Orthorhombic
- Crystal habit
- Tabular crystals, radiating clusters, drusy coatings
- Cleavage
- None
- Fluorescence
- Bright green under SW and LW UV
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In miarolitic cavities in nepheline syenite and altered pegmatite dikes in an intrusive alkalic gabbro-syenite complex (Mont Saint-Hilaire, Canada); in augite syenite (Narssârssuk, Greenland)
Where rockhounds find gaidonnayite
Classic worldwide localities
- Granite Mountain, near Little Rock, Pulaski Co., Arkansas, USA
- Mont Saint-Hilaire, near Saint-Amable, and in the She°eld Lake complex, Kipawa River, Villedieu Township, Quebec, Canada
- Narssârssuk, Greenland
- Lovozero and Khibiny massifs, Kola Peninsula, Russia
Field-hunting tip
Where it forms: In miarolitic cavities in nepheline syenite and altered pegmatite dikes in an intrusive alkalic gabbro-syenite complex (Mont Saint-Hilaire, Canada); in augite syenite (Narssârssuk, Greenland). If you start seeing siderite, analcime, hilairite in float, you are in the right ground. Typical habit: tabular crystals, radiating clusters, drusy coatings. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify gaidonnayite?+
Where is gaidonnayite found?+
What rocks look like gaidonnayite?+
What minerals are found with gaidonnayite?+
What kind of rock does gaidonnayite form in?+
What is gaidonnayite used for?+
Find gaidonnayite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
