Creedite

Ca3Al2(SO4)(OH)2F8 · 2H2O
IMA status
  • Approved
  • Grandfathered
IMA symbol
Cee
Discovered
1916
Also known as
  • Belijankit
  • Belyankit
  • Belyankita
  • +1 more

History

Creedite borrows its name from a place on the map. It was named for the Creede district of Mineral County, Colorado, the rugged silver-mining country where it was first found.

The find came in 1916. Two chemists, working a fluorite-barite vein near Wagon Wheel Gap, picked apart its rare alteration minerals and described a new species among them. That vein, at the Colorado Fluorspar Company Mine, is the type locality — the place a mineral is first formally identified. The first known creedite there sat embedded in halloysite, a soft clay mineral.

The mineral is a secondary one, meaning it does not crystallise from fresh magma or hot fluid. Instead it grows later, as a fluorite ore body weathers. The slow chemical attack of air and water on buried ore breaks the older minerals down. That intense oxidation rebuilds their calcium, aluminium and fluorine into creedite.

For decades it stayed a mineralogical curiosity. That changed with Mexico. Orange crystals reached collectors from the Santa Eulalia district of Chihuahua in the 1980s. Then, in the early 2000s, the Navidad Mine in Durango yielded its now-famous specimens: vivid orange sprays of fine needle-like prisms, clustered like a hedgehog. Violet crystals turn up at the same Mexican localities, far rarer than the orange.

Industrial & practical applications

No industrial use is recorded for creedite. It is too rare, and forms in quantities too small, to be mined for any commercial purpose.

Its value is to collectors. The mineral forms radiating sprays of fine needle-like prisms, and the best of these are prized display pieces. The vivid orange clusters from the Navidad Mine in Durango, Mexico are the most sought after; violet examples are scarcer still. Museums and study collections keep it for the same reason: as a representative example of a rare calcium-aluminium fluoride species.

Where it forms, where it's found

Geological setting

Upper portions of a fluorite-baryte vein.

Type locality
Colorado Fluorspar Company Mine
  1. Wagon Wheel Gap
  2. Mineral County
  3. Colorado
  4. USA

37.7461°, -106.8265°

49recorded occurrences
Source · OpenStreetMap

Physical

Hardness
123456789104/ 10 MOHS
  1. 1Talc
  2. 2Gypsum
  3. 3Calcite
  4. 4Fluorite
  5. 5Apatite
  6. 6Orthoclase
  7. 7Quartz
  8. 8Topaz
  9. 9Corundum
  10. 10Diamond
Lustre
Vitreous
Transparency
Transparent
Colour
white · violet · purple · colourless · orange · colourless in transmitted light.
Streak
white
Tenacity
brittle
Cleavage
Perfect

On (100).

Fracture
Conchoidal
Density
2.713 g/cm³

Optical

Optical type
Biaxial (-)
Refractive index
1.461 – 1.485
Surface relief
Low
Principal indices
nα 1.461 · nβ 1.478 · nγ 1.485
Dispersion
r > v strong
Michel-Lévy diagramhighlighted lineδ = 0.0240
Attainable Michel-Lévy rangeΔ ∈ [0, t·δmax]240 nm1st order
Δ = 0Δmax
Thin-section mosaic70 grains · random 3D orientations
PPLpleochroism per grain
XPLindependent extinctions · rotate the stage
Interference simulatorsingle grain · PPL ↔ XPL
PPLpleochroism only · colour blends on rotation
XPLinterference colour · extinct every 90°
Retardation240 nm
Order1st order
XPL colour

Crystallography

Crystal system
Monoclinic
Space group
C2/c
Cell parameters
a = 13.936(1) Å · b = 8.606(1) Å · c = 9.985(1) Å
Cell angles
β = 94.39(1) °
Ratio a:b:c
1 : 0.618 : 0.716
Z
4
Morphology

Crystals short prismatic to acicular [001]; commonly with (111) and (111) or (111) alone as the dominant terminal forms. Crystals may measure up to 8 cm. Radiated aggregates; drusy, masses; embedded grains and crystals.

Crystal structure

Chemical composition

Constituent elements
Mass composition breakdown
ElementAtoms At. mass g/mol Mass g/molMass share
9FFluorineFluorine818.998151.984
30.87%
8OOxygenOxygen815.999127.992
26.00%
20CaCalciumCalcium340.078120.234
24.43%
13AlAluminiumAluminium226.98253.964
10.96%
16SSulfurSulfur132.06032.060
6.51%
1HHydrogenHydrogen61.0086.048
1.23%
Total492.282100.00%

Mass share = atoms × atomic mass ÷ molar mass × 100

From IMA formula

Synonyms

  • Belijankit
  • Belyankit
  • Belyankita
  • Belyankite

In other languages

French
Creedite
German
Creedit
Spanish
Creedita
Italian
Creedite
Japanese
クリード石
Chinese
氟铝石膏
Russian
Кридит

Classification

Strunz
10th ed.

3.CG.15

  • 3HalidesClass
  • 3.CComplex halidesDivision
  • 3.CGAluminofluorides with CO3, SO4, PO4Group
  • 3.CG.15CreediteSpecies
Dana
8th ed.

12.01.04.01

  • 12Compound HalidesClass
  • 12.01MiscellaneousType
  • 12.01.04— unnamed intermediate level —Group
  • 12.01.04.01CreediteSpecies
CIM

26.18

  • 26Sulphates with HalideClass
  • 26.18— unnamed intermediate level —Group
  • 26.18CreediteSpecies

Literature, links & citation

Citations
  1. 1916Larsen, E.S., Wells, R.C. (1916) Some minerals from the fluorite-barite vein near Wagon Wheel Gap, Colorado. Proceedings of the National Academy of Sciences: 2: 360-365.
  2. 1916Gordon, S.G. (1916) New species. American Mineralogist: 1: 86-88.
  3. 1922Foshag, W.F. (1922) The crystallography and chemical composition of creedite. Proceedings of the U.S. National Museum: 59: 419-424.
  4. 1932American Mineralogist (1932): 17: 75.
  5. 1951Palache, Charles; Berman, Harry; Frondel, Clifford (1951) The System of Mineralogy (7th ed.) Vol. 2 - Halides, Nitrates, Borates, Carbonates, Sulfates, Phosphates, Arsenates, Tungstates, Molybdates, Etc. John Wiley and Sons.
Cite this entry
@misc{mineral2026,
  author    = {Mineral Index editorial board},
  title     = {Creedite — Mineral Index},
  year      = {2026},
  url       = {https://mineralindex.org/minerals/creedite-1151},
  note      = {Accessed 2026-05-11}
}