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
- 2.21 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
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, 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
How do you identify rapidcreekite?+
Where is rapidcreekite found?+
What rocks look like rapidcreekite?+
What minerals are found with rapidcreekite?+
What kind of rock does rapidcreekite form in?+
What is rapidcreekite used for?+
Find rapidcreekite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
