Creedite Mineral Data

Creedite Mineral Data +

General Creedite Information

Chemical Formula:

Ca3Al2(SO4)(F,OH)10·2(H2O)

Composition:

Molecular Weight = 491.30 gm

Calcium 24.47 % Ca 34.24 % CaO

Aluminum 10.98 % Al 20.75 % Al₂O₃

Hydrogen 1.33 % H 11.92 % H₂O

Sulfur 6.53 % S 16.30 % SO₃

Oxygen 27.68 % O

Fluorine 29.00 % F 29.00 % F

- % F -12.21 % -O=F₂

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Ca₃Al₂(SO₄)F_7.5(OH)_2.5·2(H₂O)

IMA Status:

Valid Species (Pre-IMA) 1916

Locality:

Wagon Wheel Gap, Creed Quadrangle, Colorado, USA. Link to MinDat.org Location Data.

Name Origin:

Named after its locality.

Synonym:

ICSD 31248

PDF Aug-72

Creedite Image

Images:

Creedite

Comments: Colorless, bladed creedite crystals.
Location: Mina Navidad, Durango, Mexico. Scale: Crystal size 1.4 cm.
© John Veevaert

Images:

Creedite Fluorite

Comments: Well-developed, prismatic, reddish creedite crystals on green fluorite.
Location: Mina Navidad, Rodeo, Durango, Mexico. Scale: 9 x 5 x 5.3 cm.
© Fabre Minerals

Images:

Creedite Smithsonite

Comments: Purple transparent crystals of creedite to 6 mm on matrix of creamy botryoidal crystalline smithsonite.
Location: Level 8 San Antonio mine, Santa Eulalia, Chihuahua, Mexico. Scale: 7 x 3.5 x 2 cm.
© Dan Weinrich

Creedite Crystallography

Axial Ratios:

a:b:c =1.5046:1:1.1655

Cell Dimensions:

a = 12.91, b = 8.58, c = 10, Z = 4; beta = 94.4° V = 1,104.41 Den(Calc)= 2.95

Crystal System:

Monoclinic - PrismaticH-M Symbol (2/m) Space Group: C 2/c

$Help on X Ray Diffraction:$ X Ray Diffraction:

By Intensity(I/I_o): 3.48(1), 6.9(0.9), 7.3(0.9),

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Forms: [ 2 0 1] [ 2 2 1] [ 1 1 0] [ 1 1 1] [ 0 0 1]

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Physical Properties of Creedite

Cleavage:

[100] Perfect

Color:

Colorless, Violet, White.

Density:

2.71

Diaphaniety:

Transparent to translucent

Fracture:

Conchoidal - Fractures developed in brittle materials characterized by smoothly curving surfaces, (e.g. quartz).

Habit:

Granular - Generally occurs as anhedral to subhedral crystals in matrix.

Habit:

Prismatic - Crystals Shaped like Slender Prisms (e.g. tourmaline).

Habit:

Radial - Crystals radiate from a center without producing stellar forms (e.g. stibnite)

Hardness:

3.5 - Copper Penny

Luminescence:

Non-fluorescent.

Luster:

Vitreous - Greasy

Streak:

white

Optical Properties of Creedite

Gladstone-Dale:

CI meas= 0.115 (Poor) - where the CI = (1-KPDmeas/KC)
CI calc= 0.187 (Poor) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.1609,KPDmeas= 0.1752,KC= 0.1979

Optical Data:

Biaxial (-), a=1.461, b=1.478, g=1.485, bire=0.0240

Calculated Properties of Creedite

Electron Density:

r_electron=2.69 gm/cc
note: r_Creedite=2.71 gm/cc.

Fermion Index

Fermion Index = 0.00095
Boson Index = 0.99905

Photoelectric:

PE_Creedite= 3.91 barns/electron
U=PE_Creedite x r_electron= 10.52 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Creedite is Not Radioactive

Creedite Classification

Dana Class:

12.1.4.1 (12)Compound Halides

(12.1)with miscellaneous anions

(12.1.4)Dana Group

12.1.4.1 Creedite Ca3Al2(SO4)(F,OH)10·2(H2O) C 2/c 2/m

Strunz Class:

III/C.01-40 III - Halogenides

III/C - Double halogenides with water, Fluorides

III/C.01 - Gearksutite - Chukhrovite - (Ce) series

III/C.01-10 Gearksutite CaAl(OH,F)5·(H2O) Mono

III/C.01-20 Acuminite SrAlF4(OH)·(H2O) C 2/c 2/m

III/C.01-30 Tikhonenkovite SrAl(OH)F4·(H2O) Unk Mono

III/C.01-35 Artroeite PbAlF3(OH)2 P1 1

III/C.01-40 Creedite Ca3Al2(SO4)(F,OH)10·2(H2O) C 2/c 2/m

III/C.01-50 Chukhrovite-(Y) Ca3(Y,Ce)Al2(SO4)F13·10(H2O) F d3 2/m 3

III/C.01-60 Chukhrovite-(Ce) Ca3(Ce,Y)Al2(SO4)F13·10(H2O) F d3 2/m 3

Other Creedite Information

References:

NAME( Ford32) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Enc. of Minerals,2nd ed.,1990)

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Creedite

Ca3Al2(SO4)(F,OH)10·2(H2O)
Dana No: 12.1.4.1 Strunz No: III/C.01-40
Locality:

Notes: