Macdonaldite Mineral Data

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General Macdonaldite Information

Chemical Formula:

BaCa4[Si16O36(OH)2]•10(H2O)

Composition:

Molecular Weight = 1,537.15 gm

Barium 8.93 % Ba 9.97 % BaO

Calcium 10.43 % Ca 14.59 % CaO

Silicon 29.23 % Si 62.54 % SiO₂

Hydrogen 1.44 % H 12.89 % H₂O

Oxygen 49.96 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

BaCa₄Si₁₆O₃₆(OH)₂•10(H₂O)

Environment:

Sanbornite-bearing metamorphic rocks near a granodiorite contact.

IMA Status:

Approved IMA 1965

Locality:

Big Creek - Rush Creek sanbornite deposit, 5 miles NE of Trimmer, Fresno Co., California. Link to MinDat.org Location Data.

Name Origin:

Named for Grodon Andrew Macdonald (1911-1978), American volcanologist, University of Hawaii.

Name Pronunciation:

Macdonaldite + Pronunciation

Synonym:

ICSD 23566

PDF 18-163

Macdonaldite Image

Images:

Macdonaldite

Comments: Bright white flattened radial macdonaldite aggregate on quartz.
Location: Rush Creek, Fresno County, California, USA. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Macdonaldite Crystallography

Axial Ratios:

a:b:c =0.5977:1:0.5561

Cell Dimensions:

a = 14.06, b = 23.52, c = 13.08, Z = 4; V = 4,325.44 Den(Calc)= 2.36

Crystal System:

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

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

By Intensity(I/I_o): 6.5(1), 4.36(0.8), 6.3(0.5),

Crystal Structure:

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Cannillo E , Rossi G , Ungaretti L , Atti della Accademia Nazionale dei Lincei , 45 (1968) p.399-414, The crystal structure of macdonaldite, Locality: Fresno County, California, USA, Note: x(Si4) corrected

Physical Properties of Macdonaldite

Cleavage:

{010} Perfect, {001} Good, {100} Indistinct

Color:

Colorless, White.

Density:

2.27

Diaphaneity:

Transparent

Habit:

Acicular - Occurs as needle-like crystals.

Hardness:

3.5-4 - Copper Penny-Fluorite

Luster:

Vitreous - Silky

Streak:

white

Optical Properties of Macdonaldite

Gladstone-Dale:

CI meas= -0.062 (Fair) - where the CI = (1-KPDmeas/KC)
CI calc= -0.022 (Excellent) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.222,KPDmeas= 0.2308,KC= 0.2173
Ncalc = 1.49 - 1.51

Optical Data:

Biaxial (+/-), a=1.518, b=1.524, g=1.53, bire=0.0120, 2V(Calc)=88, 2V(Meas)=90.

Calculated Properties of Macdonaldite

Electron Density:

Bulk Density (Electron Density)=2.35 gm/cc
note: Specific Gravity of Macdonaldite =2.36 gm/cc.

Fermion Index:

Fermion Index = 0.02
Boson Index = 0.98

Photoelectric:

PE_Macdonaldite= 38.38 barns/electron
U=PE_Macdonaldite x rElectron Density= 90.28 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Macdonaldite is Not Radioactive

Macdonaldite Classification

Dana Class:

72.05.01.03 (72)Phyllosilicate Two-Dimensional Infinite Sheets with Other Than Six-Membered Rings

(72.05)with corrugated and complex layers

(72.05.01)Rhodesite group

72.05.01.01 Rhodesite KHCa2Si8O19•5(H2O) Pmam 2/m 2/m 2/m

72.05.01.02 Monteregianite-(Y) (Na,K)6(Y,Ca)2Si16O38•10(H2O) P 2₁/m 2/m

72.05.01.03 Macdonaldite BaCa4[Si16O36(OH)2]•10(H2O) C mcm 2/m 2/m 2/m

72.05.01.04 Delhayelite (Na,K)10Ca5Al6Si32O80(Cl2,F2,SO4)3•18(H2O) Pnmm 2/m 2/m 2/m

72.05.01.05 Hydrodelhayelite KCa2AlSi7O17(OH)2•6(H2O) Pnm21 mm2

72.05.01.06 Seidite-(Ce)! Na4(Ce,Sr)2{Ti(OH)2(Si8O18)}(O,OH,F)4•5(H2O) C/2c 2/m

Strunz Class:

09.EB.05 09 - SILICATES (Germanates)

09.E - Phyllosilicates

09.EB -Double nets with 4- and 6-membered rings

09.EB.05 Macdonaldite BaCa4[Si16O36(OH)2]•10(H2O) C mcm 2/m 2/m 2/m

09.EB.05 Rhodesite KHCa2Si8O19•5(H2O) Pmam 2/m 2/m 2/m

Other Macdonaldite Information

References:

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

See Also:

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

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Macdonaldite

BaCa4[Si16O36(OH)2]•10(H2O)
Dana No: 72.05.01.03 Strunz No: 09.EB.05
Locality:

Notes: