Rapidcreekite is a rare hydrated calcium sulfate-carbonate found almost exclusively in the Rapid Creek and Big Fish River areas of the Yukon. It typically forms delicate, needle-like acicular crystals or radial sprays on phosphate-rich matrix rocks, often requiring magnification for best identification. Due to its solubility and fragility, specimens should be stored in a stable, dry environment.
Is this rapidcreekite?
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 rapidcreekite with a known reference. Rapidcreekite sits at Mohs 2 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Rapidcreekite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Rapidcreekite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: white, colorless.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: acicular or fibrous crystals, often as radial sprays.
Often confused with
Rapidcreekite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside rapidcreekite
Minerals reported to co-occur with rapidcreekite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ca₂(SO₄)(CO₃)·4H₂O
- Mohs hardness
- 2
- Density
- 2.8 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Orthorhombic
- Crystal habit
- Acicular or Fibrous Crystals, Often as Radial Sprays
- Cleavage
- Perfect
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Phosphate-rich Sedimentary Iron Formations
- Typical price
- $50-300 per specimen depending on crystal size and matrix
Where rockhounds find rapidcreekite
Classic worldwide localities
- Rapid Creek, Yukon Territory, Canada
- Big Fish River, Yukon Territory, Canada
Field-hunting tip
Look in phosphate-rich sedimentary iron formations country — that is the host setting where rapidcreekite typically forms. If you start seeing ardealite, goyazite, lazulite in float, you are in the right ground. Field specimens usually show a acicular or fibrous crystals, often as radial sprays habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find rapidcreekite on the map
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