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. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: white, colorless.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: acicular.
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
- 2.21 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Orthorhombic
- Crystal habit
- Acicular
- Cleavage
- Perfect on {010}; good on {100}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A rare secondary mineral formed along joint and bedding-plane surfaces of quartz-rich sideritic iron formation
Where rockhounds find rapidcreekite
Classic worldwide localities
- Crosscut Creek, a tributary of Rapid Creek, Yukon Territory, Canada
Field-hunting tip
Where it forms: A rare secondary mineral formed along joint and bedding-plane surfaces of quartz-rich sideritic iron formation. If you start seeing kulanite, gypsum, aragonite in float, you are in the right ground. Typical habit: acicular. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify rapidcreekite?+
Where is rapidcreekite found?+
What rocks look like rapidcreekite?+
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Find rapidcreekite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
