Calciohilairite is a rare member of the hilairite group characterized by its rhombohedral crystal habit and often translucent to transparent appearance. It is primarily found as a late-stage mineral in alkaline intrusive complexes, most notably at the famous Mont Saint-Hilaire locality where it occurs in cavities.
Is this calciohilairite?
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 calciohilairite with a known reference. Calciohilairite sits at Mohs 4, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Calciohilairite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Calciohilairite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: yellow, brown, colorless.
- 5Look at form & habitCrystal system: trigonal. Typical habit: rhombohedral crystals, sometimes rounded or barrel-shaped.
Often confused with
Calciohilairite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Zircon is the harder of the two (Mohs 7.5 vs. 4); luster reads vitreous on Calciohilairite and adamantine on Zircon.
How to tell apart: Catapleiite is the harder of the two (Mohs 5.5-6 vs. 4).
Often found alongside calciohilairite
Minerals reported to co-occur with calciohilairite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaZrSi₃O₉·3H₂O
- Mohs hardness
- 4
- Density
- 2.71 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Trigonal
- Crystal habit
- Rhombohedral Crystals, Sometimes Rounded or Barrel-shaped
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Alkaline Igneous Rocks, Specifically Pegmatites and Miarolitic Cavities
- Typical price
- $50-300 per specimen depending on crystal quality and matrix
Where rockhounds find calciohilairite
Classic worldwide localities
- Mont Saint-Hilaire, Quebec, Canada
- Khibiny Massif, Kola Peninsula, Russia
Field-hunting tip
Look in alkaline igneous rocks, specifically pegmatites and miarolitic cavities country, the host setting where calciohilairite typically forms. If you start seeing aegirine, microcline, nepheline in float, you are in the right ground. Field specimens usually show a rhombohedral crystals, sometimes rounded or barrel-shaped habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify calciohilairite?+
Where is calciohilairite found?+
How much is calciohilairite worth?+
What rocks look like calciohilairite?+
What minerals are found with calciohilairite?+
What kind of rock does calciohilairite form in?+
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Find calciohilairite on the map
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