Macdonaldite
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Gordon A. Macdonald
Formula:
BaCa4Si16O36(OH)2 · 10H2O
System:
Orthorhombic
Colour:
White, colourless.
Lustre:
Vitreous, Silky
Hardness:
3½ - 4
Name:
Named in honour of Gordon A. Macdonald (15 October 1911 – 20 June 1978), notable American volcanologist and Senior Professor of Geology at the University of Hawaii at the time of the description. His 1938 Ph.D. thesis "Geology of the Western Sierra Nevada Between Kings and San Joaquin Rivers, California" included this area.
This page provides mineralogical data about Macdonaldite.
Classification of Macdonaldite
Approved
8/H.38-50
9.EB.05
9 : SILICATES (Germanates)
E : Phyllosilicates
B : Double nets with 4- and 6-membered rings
9 : SILICATES (Germanates)
E : Phyllosilicates
B : Double nets with 4- and 6-membered rings
72.5.1.3
72 : PHYLLOSILICATES Two-Dimensional Infinite Sheets with Other Than Six-Membered Rings
5 : Two-Dimensional Infinite Sheets with Other Than Six-Membered Rings with corrugated and complex layers
72 : PHYLLOSILICATES Two-Dimensional Infinite Sheets with Other Than Six-Membered Rings
5 : Two-Dimensional Infinite Sheets with Other Than Six-Membered Rings with corrugated and complex layers
14.7.4
14 : Silicates not Containing Aluminum
7 : Silicates of Ba, Sr and Zn
14 : Silicates not Containing Aluminum
7 : Silicates of Ba, Sr and Zn
Physical Properties of Macdonaldite
Vitreous, Silky
Colour:
White, colourless.
Hardness (Mohs):
3½ - 4
Optical Data of Macdonaldite
Type:
Biaxial (+/-)
RI values:
nα = 1.518 nβ = 1.524 nγ = 1.530
2V:
Measured: 90° , Calculated: 88°
Max Birefringence:
δ = 0.012
Image shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:
Low
Dispersion:
weak
Chemical Properties of Macdonaldite
Formula:
BaCa4Si16O36(OH)2 · 10H2O
Common Impurities:
Ti,Al,Fe,Mn,Mg,Sr
Crystallography of Macdonaldite
Crystal System:
Orthorhombic
Cell Parameters:
a = 14.06 Å, b = 23.52 Å, c = 13.08 Å
Ratio:
a:b:c = 0.598 : 1 : 0.556
Unit Cell Volume:
V 4,325.44 ų (Calculated from Unit Cell)
Type Occurrence of Macdonaldite
Co-type Localities:
Big Creek, Rush Creek deposit, Big Creek-Rush Creek District, Fresno Co., California, USA
Esquire No. 7 claim, Big Creek, Rush Creek deposit, Big Creek-Rush Creek District, Fresno Co., California, USA
Esquire No. 1 claim, Rush Creek, Rush Creek deposit, Big Creek-Rush Creek District, Fresno Co., California, USA
Esquire No. 7 claim, Big Creek, Rush Creek deposit, Big Creek-Rush Creek District, Fresno Co., California, USA
Esquire No. 1 claim, Rush Creek, Rush Creek deposit, Big Creek-Rush Creek District, Fresno Co., California, USA
Relationship of Macdonaldite to other Species
| 9.EB.05 | Rhodesite | K2Ca2Si8O19 · 5H2O |
| 9.EB.10 | Delhayelite | K7Na3Ca5Al2Si14O38F4Cl2 |
| 9.EB.10 | Hydrodelhayelite | KCa2(Si7Al)O17(OH)2 · 6H2O |
| 9.EB.15 | Monteregianite-(Y) | KNa2YSi8O19 · 5H2O |
| 9.EB.20 | Carletonite | KNa4Ca4Si8O18(CO3)4(F,OH) · H2O |
| 14.7.1 | Sanbornite | BaSi2O5 |
| 14.7.2 | Krauskopfite | BaSi2O5 · 3H2O |
| 14.7.3 | Walstromite | BaCa2Si3O9 |
| 14.7.5 | Ericssonite | BaMn22+Fe3+(Si2O7)O(OH) |
| 14.7.6 | Ericssonite-2O | BaMn22+Fe3+(Si2O7)O(OH) |
| 14.7.7 | Gillespite | BaFe2+Si4O10 |
| 14.7.8 | Andrémeyerite | BaFe22+Si2O7 |
| 14.7.9 | Pellyite | Ba2CaFe22+Si6O17 |
| 14.7.10 | Taikanite | BaSr2Mn23+O2(Si4O12) |
| 14.7.11 | Willemite | Zn2SiO4 |
| 14.7.12 | Hemimorphite | Zn4Si2O7(OH)2 · H2O |
| 14.7.13 | Zincsilite | Zn3Si4O10(OH)2 · 4H2O |
| 14.7.14 | Hardystonite | Ca2ZnSi2O7 |
| 14.7.15 | Petedunnite | CaZnSi2O6 |
| 14.7.16 | Clinohedrite | CaZnSiO4 · H2O |
| 14.7.17 | Junitoite | CaZn2Si2O7 · H2O |
| 14.7.18 | Larsenite | PbZnSiO4 |
| 14.7.19 | Esperite | PbCa2(ZnSiO4)3 |
| 14.7.20 | Hodgkinsonite | Zn2Mn2+SiO4(OH)2 |
| 14.7.21 | Gerstmannite | Mn2+MgZnSiO4(OH)2 |
| 14.7.22 | Gageite | Mn212+Si8O27(OH)20 |
| 14.7.23 | Franklinfurnaceite | Ca2Mn32+Mn3+Fe3+Zn2Si2O10(OH)8 |
Other Names for Macdonaldite
Name in Other Languages:
German:Macdonaldit
Russian:Макдональдит
Simplified Chinese:莫水硅钙钡石
Spanish:Macdonaldita
Traditional Chinese:莫水矽鈣鋇石
Other Information
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
References for Macdonaldite
Reference List:
American Mineralogist (1965): 50: 314-340.
Internet Links for Macdonaldite
mindat.org URL:
https://www.mindat.org/min-2506.html
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External Links:
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Localities for Macdonaldite
This map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the 
symbol to view information about a locality.
The symbol next to localities in the list
can be used to jump to that position on the map.
symbol to view information about a locality.
The symbol next to localities in the list
can be used to jump to that position on the map.
(TL) indicates type locality for a valid mineral species. (FRL) indicates first recorded locality for everything else. ? indicates mineral may be doubtful at this locality. All other localities listed without reference should be considered as uncertain and unproven until references can be found.
Italy | |
| Stoppa, F., Sharygin, V.V., and Cundari, A. (1997): Mineralogy and Petrology 61, 27-45. |
USA | |
| Alfors, J.T., M.C. Stinson, R.A. Matthews & A. Pabst (1965), Seven new barium minerals from eastern Fresno County, California: American Mineralogist: 50: 318, 322-324; Pemberton, H. Earl (1983), Minerals of California; Van Nostrand Reinholt Press: 464. |
| Stinson, Melvin Clarence & J.T. Alfors (1964), New minerals from Fresno County – I: California Division Mines & Geology Mineral Information Service.: 17: 238; Nickel & Nichols (1991), Mineral Reference Manual: 124: | |
| [Amer.Min.(1965) 50, 314-340; MinRec 33:161]; Canadian Mineralogist (2001): 39:1053-1058. |
| Bob Walstrom, p.c. | |
| [Nickel & Nichols, 1991 - "Mineral Reference Manual", p123] |
| [MinRec 30:414] |
| Mineralogical Record: 34(2): 159-166 |
Big Creek, Rush Creek deposit, Big Creek-Rush Creek District, Fresno Co., California, USA