Fairchildite Mineral Data

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General Fairchildite Information

Chemical Formula:

K2Ca(CO3)2

Composition:

Molecular Weight = 238.29 gm

Potassium 32.82 % K 39.53 % K₂O

Calcium 16.82 % Ca 23.53 % CaO

Carbon 10.08 % C 36.94 % CO₂

Oxygen 40.29 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

K₂Ca(CO₃)₂

Environment:

Dimorph with butschliite. The samples are fused wood-ash clinkers that occurs in partly burned fir and hemlock trees in many national parks and forest in the western United States.

IMA Status:

Valid Species (Pre-IMA) 1949

Locality:

Link to MinDat.org Location Data.

Name Origin:

Named after John Gifford Fairchild (1882-1965), analytical chemist at the U. S. Geological Survey.

Name Pronunciation:

Fairchildite + Pronunciation

Synonym:

ICSD 100845

PDF 21-1287

Fairchildite Image

Images:

Fairchildite

Comments: PPL thin-section image of fused wood-ash stone, showing slightly altered lath-shaped cross-sections of fairchildite in a fine groundmass containing buetschliite and calcite. Inset image shows sample.
Location: Kaniksu National Forest, Idaho. (AmMin, v32:607). Scale: Thin Section 30 X.
© American Mineralogist

Fairchildite Crystallography

Axial Ratios:

a:c = 1:2.51896

Cell Dimensions:

a = 5.272, c = 13.28, Z = 2; V = 319.65 Den(Calc)= 2.48

Crystal System:

Hexagonal - Dihexagonal DipyramidalH-M Symbol (6/m 2/m 2/m) Space Group: P 6₃/mmc

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

By Intensity(I/I_o): 3.19(1), 2.64(0.8), 6.64(0.5),

Crystal Structure:

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Pertlik F , Zeitschrift fur Kristallographie , 157 (1981) p.199-205, Structural investigations of synthetic fairchildite, K2Ca(CO3)2, Locality: synthetic, Note: y(O1) changed to satisfy symmetry constraints

Physical Properties of Fairchildite

Cleavage:

{0001} Good

Color:

Colorless.

Density:

2.446

Diaphaneity:

Transparent

Habit:

Platy - Sheet forms (e.g. micas).

Hardness:

2.5 - Finger Nail

Luster:

Vitreous (Glassy)

Streak:

white

Optical Properties of Fairchildite

Gladstone-Dale:

CI meas= -0.008 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= 0.006 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2036,KPDmeas= 0.2065,KC= 0.2048
Ncalc = 1.5 - 1.51

Optical Data:

Uniaxial (-), e=1.478, w=1.532, bire=0.0540.

Calculated Properties of Fairchildite

Electron Density:

Bulk Density (Electron Density)=2.46 gm/cc
note: Specific Gravity of Fairchildite =2.48 gm/cc.

Fermion Index:

Fermion Index = 0.0015686955
Boson Index = 0.9984313045

Photoelectric:

PE_Fairchildite= 5.47 barns/electron
U=PE_Fairchildite x r_electron= 13.44 barns/cc.

Radioactivity:

GRapi = 468.92 (Gamma Ray American Petroleum Institute Units)
Concentration of Fairchildite per GRapi unit = 0.21 (%)

Estimated Radioactivity from Fairchildite - barely detectable

Fairchildite Classification

Dana Class:

14.03.03.01 (14)Anhydrous Carbonates

(14.03)with Compound Formula A+2 B++ (CO3)2

(14.03.03)Fairchildite Series

14.03.03.01 Fairchildite K2Ca(CO3)2 P 6₃/mmc 6/m 2/m 2/m

14.03.03.02 Zemkorite (Na,K)2Ca(CO3)2 P 6₃/mmc, P 6₃mc, P 6₂c- Hex

Strunz Class:

05.AC.20 05 - CARBONATES (NITRATES)

05.A - Carbonates without additional anions, without H2O

05.AC -Alkali and alkali-earth carbonates

05.AC.20 Fairchildite K2Ca(CO3)2 P 6₃/mmc 6/m 2/m 2/m

Other Fairchildite Information

References:

NAME( Dana8) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Enc. of Minerals,2nd ed.,1990)

See Also:

Links to other databases for Fairchildite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - EUROmin Project
4 - Ecole des Mines de Paris
5 - Google Images
6 - Google Scholar
7 - Handbook of Mineralogy (MinSocAm)
8 - Handbook of Mineralogy (UofA)
9 - MinDAT
10 - MinMax(Deutsch)
11 - MinMax(English)
12 - Mineralienatlas (Deutsch)
13 - QUT Mineral Atlas
14 - Ruff.Info
15 - WWW-MINCRYST

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Print or Cut-and-Paste your Fairchildite Specimen Label here :

Fairchildite

K2Ca(CO3)2
Dana No: 14.03.03.01 Strunz No: 05.AC.20
Locality:

Notes: