SUPPORT US. Covid-19 has significantly affected our fundraising. Please help!
Log InRegister
Home PageAbout MindatThe Mindat ManualHistory of MindatCopyright StatusWho We AreContact UsAdvertise on Mindat
Donate to MindatCorporate SponsorshipSponsor a PageSponsored PagesMindat AdvertisersAdvertise on Mindat
Learning CenterWhat is a mineral?The most common minerals on earthInformation for EducatorsMindat ArticlesThe ElementsBooks & Magazines
Minerals by PropertiesMinerals by ChemistryAdvanced Locality SearchRandom MineralRandom LocalitySearch by minIDLocalities Near MeSearch ArticlesSearch GlossaryMore Search Options
Search For:
Mineral Name:
Locality Name:
The Mindat ManualAdd a New PhotoRate PhotosLocality Edit ReportCoordinate Completion ReportAdd Glossary Item
Mining CompaniesStatisticsUsersMineral MuseumsMineral Shows & EventsThe Mindat DirectoryDevice Settings
Photo SearchPhoto GalleriesNew Photos TodayNew Photos YesterdayMembers' Photo GalleriesPast Photo of the Day GalleryMineral Photography


This page is currently not sponsored. Click here to sponsor this page.
Hide all sections | Show all sections

About MacdonalditeHide

Gordon A. Macdonald
BaCa4Si16O36(OH)2 · 10H2O
White, colourless.
Vitreous, Silky
3½ - 4
Crystal System:
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 MacdonalditeHide


9 : SILICATES (Germanates)
E : Phyllosilicates
B : Double nets with 4- and 6-membered rings

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 : Silicates not Containing Aluminum
7 : Silicates of Ba, Sr and Zn

Physical Properties of MacdonalditeHide

Vitreous, Silky
White, colourless.
3½ - 4 on Mohs scale

Optical Data of MacdonalditeHide

Biaxial (+/-)
RI values:
nα = 1.518 nβ = 1.524 nγ = 1.530
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:

Chemical Properties of MacdonalditeHide

BaCa4Si16O36(OH)2 · 10H2O
Common Impurities:

Crystallography of MacdonalditeHide

Crystal System:
Cell Parameters:
a = 14.06 Å, b = 23.52 Å, c = 13.08 Å
a:b:c = 0.598 : 1 : 0.556
Unit Cell V:
4,325.44 ų (Calculated from Unit Cell)

Crystal StructureHide

Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Big Balls | Small Balls | Just Balls | Spacefill
Polyhedra Off | Si Polyhedra | All Polyhedra
Remove metal-metal sticks
Display Options
Black Background | White Background
Perspective On | Perspective Off
2D | Stereo | Red-Blue | Red-Cyan
CIF File    Best | x | y | z | a | b | c
Stop | Start
Console Off | On | Grey | Yellow
IDSpeciesReferenceLinkYearLocalityPressure (GPa)Temp (K)
0012053MacdonalditeCannillo E, Rossi G, Ungaretti L (1968) The crystal structure of macdonaldite Atti della Accademia Nazionale dei Lincei 45 399-4141968Fresno County, California, USA0293
CIF Raw Data - click here to close

Type Occurrence of MacdonalditeHide

Synonyms of MacdonalditeHide

Other Language Names for MacdonalditeHide

Simplified Chinese:莫水硅钙钡石
Traditional Chinese:莫水矽鈣鋇石

Common AssociatesHide

Associated Minerals Based on Photo Data:
1 photo of Macdonaldite associated with KampfiteBa12(Si11Al5)O31(CO3)8Cl5

Related Minerals - Nickel-Strunz GroupingHide

9.EB.05RhodesiteKHCa2Si8O19 · 5H2OOrth. mmm (2/m 2/m 2/m)
9.EB.10Delhayelite(Na,K)10Ca5Al6Si32O80(Cl2,F2,SO4)3 · 18H2OOrth.
9.EB.10HydrodelhayeliteKCa2AlSi7O17(OH)2 · 6H2OOrth.
9.EB.15Monteregianite-(Y)(Na,K)6(Y,Ca)2Si16O38 · 10H2OMon. 2/m
9.EB.20CarletoniteKNa4Ca4Si8O18(CO3)4(OH,F) · H2OTet. 4/mmm (4/m 2/m 2/m) : P4/mbm

Related Minerals - Dana Grouping (8th Ed.)Hide · 5H2OOrth. mmm (2/m 2/m 2/m),K)6(Y,Ca)2Si16O38 · 10H2OMon. 2/m,K)10Ca5Al6Si32O80(Cl2,F2,SO4)3 · 18H2OOrth. · 6H2OOrth.

Related Minerals - Hey's Chemical Index of Minerals GroupingHide

14.7.2KrauskopfiteBaSi2O5 · 3H2OMon.
14.7.5EricssoniteBaMn2+2Fe3+(Si2O7)O(OH)Mon. 2/m : B2/m
14.7.11WillemiteZn2SiO4Trig. 3 : R3
14.7.12HemimorphiteZn4Si2O7(OH)2 · H2OOrth. mm2 : Imm2
14.7.13ZincsiliteZn3Si4O10(OH)2 · 4H2O (?)Mon.
14.7.14HardystoniteCa2Zn(Si2O7)Tet. 4 2m : P4 21m
14.7.16ClinohedriteCaZn(SiO4) · H2OMon. m : Bb
14.7.17JunitoiteCaZn2Si2O7 · H2OOrth. mm2
14.7.18LarsenitePbZnSiO4Orth. mm2 : Pna21
14.7.19EsperitePbCa2Zn3(SiO4)3Mon. 2/m : P21/b
14.7.22GageiteMn21(Si4O12)2O3(OH)20Mon. 2/m
14.7.23FranklinfurnaceiteCa2Fe3+Mn2+3Mn3+(Zn2Si2O10)(OH)8Mon. 2 : B2

Other InformationHide

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 MacdonalditeHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
American Mineralogist (1965): 50: 314-340.

Internet Links for MacdonalditeHide

Localities for MacdonalditeHide

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.

Locality ListHide

- This locality has map coordinates listed. - This locality has estimated coordinates. ⓘ - Click for further information on this occurrence. ? - Indicates mineral may be doubtful at this locality. - Good crystals or important locality for species. - World class for species or very significant. (TL) - Type Locality for a valid mineral species. (FRL) - First Recorded Locality for everything else (eg varieties). Struck out - Mineral was erroneously reported from this locality. Faded * - Never found at this locality but inferred to have existed at some point in the past (eg from pseudomorphs.)

All localities listed without proper references should be considered as questionable.
  • Umbria
    • Terni Province
      • San Venanzo
Stoppa, F., Sharygin, V.V., and Cundari, A. (1997): Mineralogy and Petrology 61, 27-45.; Stoppa, F., & Schiazza, M. (2014). Extreme chemical conditions of crystallisation of Umbrian Melilitolites and wealth of rare, late stage/hydrothermal minerals. Central European Journal of Geosciences, 6(4), 549-564.; Conticelli, S., D’antonio, M., Pinarelli, L., & Civetta, L. (2002). Source contamination and mantle heterogeneity in the genesis of Italian potassic and ultrapotassic volcanic rocks: Sr–Nd–Pb isotope data from Roman Province and Southern Tuscany. Mineralogy and Petrology, 74(2-4), 189-222. Cundari, A., & Ferguson, A. K. (1991). Petrogenetic relationships between melilitite and lamproite. Contributions to Mineralogy and Petrology, 107(3), 343-357. Laurenzi, M., Stoppa, F., & Villa, I. (1994). Eventi ignei monogenici e depositi piroclastici nel Distretto Ultra-alcalino Umbro-Laziale (ULUD): revisione, aggiornamento e comparazione dei dati cronologici. Plinius, 12, 61-65. Panina, L. I., Stoppa, F., & Usol tseva, L. M. (2003). Genesis of melilitite rocks of Pian di Celle volcano, Umbrian kamafugite province, Italy: evidence from melt inclusions in minerals. PETROLOGY C/C OF PETROLOGIIA, 11(4), 365-382. Sabatini, V. (1899). I vulcani di San Venanzo. Riv Miner Cristal It, 22, 3-12. Stoppa, F. (1996). The San Venanzo maar and tuff ring, Umbria, Italy: eruptive behaviour of a carbonatite-melilitite volcano. Bulletin of Volcanology, 57(7), 563-577. Stoppa, F., Rukhlov, A. S., Bell, K., Schiazza, M., & Vichi, G. (2014). Lamprophyres of Italy: early Cretaceous alkaline lamprophyres of southern Tuscany, Italy. Lithos, 188, 97-112. Stoppa, F., Sharygin, V. V., & Cundari, A. (1997). New mineral data from the kamafugitecarbonatite association: the melilitolite from Pian di Celle, Italy. Mineralogy and Petrology, 61(1-4), 27-45.
  • California
    • Fresno Co.
      • Big Creek-Rush Creek Mining District
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.
          • Rush Creek
Robert E. Walstrom Collection
Nickel and Nichols (1991) Mineral Reference Manual, 123.; Jambor, J.L. and Roberts, A.C. (2002) New mineral names. American Mineralogist: 87: 765-768.
Robert E. Walstrom Collection
    • Mariposa Co.
      • East Belt
        • Clearing House Mining District
          • Clearing House
            • Trumbull Peak
[MinRec 30:414]
    • Tulare Co.
      • Dumtah
Mineralogical Record: 34(2): 159-166
Robert E. Walstrom Collection
Mineral and/or Locality is an outreach project of the Hudson Institute of Mineralogy, a 501(c)(3) not-for-profit organization. Public Relations by Blytheweigh.
Copyright © and the Hudson Institute of Mineralogy 1993-2020, except where stated. Most political location boundaries are © OpenStreetMap contributors. relies on the contributions of thousands of members and supporters.
Privacy Policy - Terms & Conditions - Contact Us Current server date and time: August 10, 2020 10:15:13 Page generated: July 22, 2020 18:36:51
Go to top of page