Fairchildite Mineral Data

Fairchildite Mineral Data +

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.

Synonym:

ICSD 100845

PDF 21-1287

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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

Diaphaniety:

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

Optical Data:

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

Calculated Properties of Fairchildite

Electron Density:

r_electron=2.46 gm/cc
note: r_Fairchildite=2.48 gm/cc.

Fermion Index

Fermion Index = 0.00156
Boson Index = 0.99844

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)

Estimated Radioactivity from Fairchildite - barely detectable

Fairchildite Classification

Dana Class:

14.3.3.1 (14)Anhydrous Carbonates

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

(14.3.3)Dana Group

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

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

Strunz Class:

V/B.05-50 V - Nitrates, Carbonates and Borates

V/B - Waterfree carbonates [CO3]2- without unfamiliar anions

V/B.05 - Eitelie - Shortite - Carbocernaite series

V/B.05-10 Eitelite Na2Mg(CO3)2 R 3 3

V/B.05-20 Nyerereite Na2Ca(CO3)2 C mc2₁ mm2

V/B.05-30 Natrofairchildite Na2Ca(CO3)2 P 6₃/mmc 6/m 2/m 2/m

V/B.05-40 Gregoryite (Na2,K2,Ca)CO3 P 6₃mc 6mm

V/B.05-50 Fairchildite K2Ca(CO3)2 P 6₃/mmc 6/m 2/m 2/m

V/B.05-55 Zemkorite (Na,K)2Ca(CO3)2 P 6₃/mmc, P 6₃mc, P 6₂c- Hex

V/B.05-60 Butschliite K2Ca(CO3)2 R 3m 3 2/m

V/B.05-70 Shortite Na2Ca2(CO3)3 Amm2 mm2

V/B.05-80 Sahamalite-(Ce) (Mg,Fe)Ce2(CO3)4 P 2₁/a 2/m

V/B.05-90 Remondite-(Ce) Na3(Ce,La,Ca,Na,Sr)3(CO3)5 P 2₁ 2

V/B.05-92 Remondite-(La)! Na3(La,Ce,Ca)3(CO3)5 P 2₁ 2

V/B.05-95 Petersenite-(Ce) (Na,Ca)4(Ce,La,Nd)2(CO3)5 P 2₁ 2

V/B.05-98 Calcioburbankite Na3(Ca,REE,Sr)3(CO3)5 P 6₃mc 6mm

V/B.05-100 Burbankite (Na,Ca)3(Sr,Ba,Ce)3(CO3)5 P 6₃/mmc 6/m 2/m 2/m

V/B.05-110 Khanneshite (NaCa)3(Ba,Sr,Ce,Ca)3(CO3)5 P 6₃mc 6mm

V/B.05-120 Carbocernaite (Ca,Na)(Sr,Ce,Ba)(CO3)2 P mc2₁ mm2

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 -Google Images 5 -Google Scholar 6 -Handbook of Mineralogy (UofA) 7 -MinDAT 8 -MinMax(Deutsch) 9 -MinMax(English) 10 -Mineralienatlas (Deutsch) 11 -QUT Mineral Atlas 12 - WWW-MINCRYST 13 -École des Mines de Paris

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

Fairchildite

K2Ca(CO3)2
Dana No: 14.3.3.1 Strunz No: V/B.05-50
Locality:

Notes: