Macdonaldite Mineral Data
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 % H2 O
Oxygen 49.96 % O
______ ______
100.00 % 100.00 % = TOTAL OXIDE
Empirical Formula:
BaCa4 Si16 O36 (OH)2 •10(H2 O)
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 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 - Dipyramidal H-M Symbol (2/m 2/m 2/m) Space Group: C mcm
X Ray Diffraction:
By Intensity(I/Io ): 6.5(1), 4.36(0.8), 6.3(0.5),
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:
PEMacdonaldite = 38.38 barns/electronU=PEMacdonaldite x r Electron 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:
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