Defernite Mineral Data

Defernite Mineral Data +

General Defernite Information

Chemical Formula:

Ca6(CO3)2-x(SiO4)x(OH)7(Cl,OH)1-2x (x=0,5)

Composition:

Molecular Weight = 521.80 gm

Calcium 46.08 % Ca 64.48 % CaO

Silicon 2.69 % Si 5.76 % SiO₂

Hydrogen 1.45 % H 12.95 % H₂O

Carbon 3.45 % C 12.65 % CO₂

Chlorine 3.40 % Cl 3.40 % Cl

- % Cl -0.77 % -O=Cl₂

Oxygen 42.93 % O

______ ______

100.00 % 98.47 % = TOTAL OXIDE

Empirical Formula:

Ca₆(CO₃)_1.5(SiO₄)_0.5(OH)_7.5Cl_0.5

IMA Status:

Approved IMA 1978

Locality:

Link to MinDat.org Location Data.

Synonym:

ICSD 81638

PDF 42-1324

Defernite Image

Images:

Defernite Hematite

Comments: Specular hematite rich with crystalline grains of reddish brown defernite.
Location: Kombat Mine, Kombat, Grootfontein District, Otjozondjupa Region, Namibia. Scale: 3.9 x 2.5 cm.
© John Veevaert

Images:

Defernite Vaterite Manganite

Comments: Opaque white fibrous vaterite with red defernite and black manganite.
Location: Kombat Mine, Otavi, Otjozondjupa, Namibia. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Defernite Crystallography

Axial Ratios:

a:b:c =0.7829:1:0.1594

Cell Dimensions:

a = 17.82, b = 22.76, c = 3.629, Z = 4; V = 1,471.86 Den(Calc)= 2.35

Crystal System:

Orthorhombic - DipyramidalH-M Symbol (2/m 2/m 2/m) Space Group: Pnam

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

By Intensity(I/I_o): 11.37(1), 2.899(0.5), 3.045(0.4),

Crystal Structure:

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Peacor D R , Sarp H , Dunn P J , Innes J , Nelen J A , American Mineralogist , 73 (1988) p.888-893, Defernite from the Kombat mine, Namibia: A second occurence, structure, refinement, and crystal chemistry

View Additional jPOWD Structure files for Defernite
[1]

Physical Properties of Defernite

Cleavage:

[010] Perfect, [100] Distinct

Color:

Colorless, Reddish brown.

Density:

2.5

Diaphaniety:

Transparent

Hardness:

3 - Calcite

Luster:

Vitreous (Glassy)

Streak:

white

Optical Properties of Defernite

Gladstone-Dale:

CI meas= 0.013 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= -0.05 (Good) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2403,KPDmeas= 0.2259,KC= 0.2288

Optical Data:

Biaxial (-), a=1.546, b=1.572, g=1.576, bire=0.0300, 2V(Calc)=42, 2V(Meas)=42.

Calculated Properties of Defernite

Electron Density:

r_electron=2.53 gm/cc
note: r_Defernite=2.50 gm/cc.

Fermion Index

Fermion Index = 0.00246
Boson Index = 0.99754

Photoelectric:

PE_Defernite= 5.99 barns/electron
U=PE_Defernite x r_electron= 15.14 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Defernite is Not Radioactive

Defernite Classification

Dana Class:

16b.4.2.1 (16b)Carbonates - Hydroxyl or Halogen

(16b.4)where (A)m (B)n (XO3)p Zq · x(H2O), with (m+n):p=8:1

(16b.4.2)Dana Group

16b.4.2.1 Defernite Ca6(CO3)2-x(SiO4)x(OH)7(Cl,OH)1-2x(x=0,5) Pnam 2/m 2/m 2/m

16b.4.2.2 Holdawayite Mn6(CO3)2(OH)7(Cl,OH) C 2/m 2/m

Strunz Class:

V/C.06-30 V - Nitrates, Carbonates and Borates

V/C - Waterfree carbonates with unfamiliar anions

V/C.06 - Brenkite - Defernite series

V/C.06-10 Brenkite Ca2(CO3)F2 P bcn 2/m 2/m 2/m

V/C.06-20 Holdawayite Mn6(CO3)2(OH)7(Cl,OH) C 2/m 2/m

V/C.06-25 Rouvilleite Na3Ca2(CO3)3F Cc,C 2/c Mono

V/C.06-27 Sheldrickite! NaCa3(CO3)2F3·(H2O) P 3₂ 3

V/C.06-30 Defernite Ca6(CO3)2-x(SiO4)x(OH)7(Cl,OH)1-2x(x=0,5) Pnam 2/m 2/m 2/m

Other Defernite Information

References:

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

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Defernite

Ca6(CO3)2-x(SiO4)x(OH)7(Cl,OH)1-2x (x=0,5)
Dana No: 16b.4.2.1 Strunz No: V/C.06-30
Locality:

Notes: