Vuagnatite is a rare calcium aluminum silicate typically found as small, translucent green to yellow-green prismatic crystals. It is almost exclusively found in rodingites associated with ophiolitic rocks and is highly sought after by systematic mineral collectors. It is visually similar to prehnite but can be distinguished through analytical testing or distinct crystal habits.
Is this vuagnatite?
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 vuagnatite with a known reference. Vuagnatite sits at Mohs 6.5-7 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Vuagnatite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Vuagnatite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: green, yellow-green, colorless.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: prismatic to acicular crystals, often as radial aggregates or massive.
Often confused with
Vuagnatite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside vuagnatite
Minerals reported to co-occur with vuagnatite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaAlSiO₄(OH)
- Mohs hardness
- 6.5-7
- Density
- 3.28-3.32 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Orthorhombic
- Crystal habit
- Prismatic to Acicular Crystals, Often as Radial Aggregates or Massive
- Cleavage
- Distinct On {110}
- Rarity
- Rare
- Uses
- Collector, Lapidary
- Host rock
- Rodingite Dikes in Ophiolite Complexes
- Typical price
- $20-100 for small study specimens
Where rockhounds find vuagnatite
Classic worldwide localities
- Vuagnat, Haute-Savoie, France
- Sarany, Ural Mountains, Russia
- Guanajuato, Mexico
- South Africa
Field-hunting tip
Look in rodingite dikes in ophiolite complexes country — that is the host setting where vuagnatite typically forms. If you start seeing prehnite, grossular, diopside in float, you are in the right ground. Field specimens usually show a prismatic to acicular crystals, often as radial aggregates or massive habit, so train your eye for that shape before scanning the outcrop.
Common questions
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How much is vuagnatite worth?+
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Find vuagnatite on the map
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