Tweddillite (original) (raw)

A valid IMA mineral species

About TweddilliteHide

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Formula:

(CaSr)(Mn3+AlMn3+)O[Si2O7][SiO4](OH)

Specific Gravity:

3.84 (Calculated)

Crystal System:

Monoclinic

Name:

Named by T. Armbruster et al. in 2002 in honor of Samuel Milbourn Tweddill (3 April 1852, Scarborough, Yorkshire, England - 4 July 1917, Groenvlei Tin Mine, Limpopo, South Africa), the first curator of the Pretoria Geological Museum from 1897 to 1916. It was renamed manganipiemontite-(Sr) by the Epidote Subcommittee of the CNMMN in 2006 and reverted to tweddillite in 2015.

Unique IdentifiersHide

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Long-form identifier:

mindat:1:1:11118:0

6cdccbe6-1729-4d8d-bd33-5583ecd1ddba

IMA Classification of TweddilliteHide

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IMA Formula:

CaSr(Mn3+2Al)[Si2O7][SiO4]O(OH)

Approval history:

Originally called tweddillite; renamed manganipiemontite-(Sr) by the Epidote Subcommittee of the CNMMN in 2006; reverted to tweddillite in 2015.

Type description reference:

Armbruster, T., Gnos, E., Dixon, R., Gutzmer, J., Hejny, C., Döbelin, N., Medenbach, O. (2002) Manganvesuvianite and tweddillite, two new Mn3+-silicate minerals from the Kalahari manganese fields, South Africa. Mineralogical Magazine, 66 (1) 137-150 doi:10.1180/0026461026610018

Classification of TweddilliteHide

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9.BG.05

9 : SILICATES (Germanates)
B : Sorosilicates
G : Sorosilicates with mixed SiO4 and Si2O7 groups; cations in octahedral [6] and greater coordination

Mineral SymbolsHide

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As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.

Physical Properties of TweddilliteHide

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Cleavage:

Perfect
perfect after {001}

Density:

3.84(3) g/cm3 (Calculated)

Optical Data of TweddilliteHide

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Comments:

Within the (001) blades, the crystals appear dark red parallel to b and orange-yellow parallel to a. Perpendicular to (001) the blades appear magenta to red.

Comments:

Average RI = 1.825.

Chemistry of TweddilliteHide

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Mindat Formula:

(CaSr)(Mn3+AlMn3+)O[Si2O7][SiO4](OH)

Chemical AnalysisHide

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Crystallography of TweddilliteHide

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Crystal System:

Monoclinic

Class (H-M):

2/m - Prismatic

Cell Parameters:

a = 8.932(5) Å, b = 5.698(4) Å, c = 10.310(5) Å
β = 114.56(4)°

Ratio:

a:b:c = 1.568 : 1 : 1.809

Unit Cell V:

477.25 ų (Calculated from Unit Cell)

Twinning:

All crystals are (100) twinned.

Crystal StructureHide

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ID	Species	Reference	Link	Year	Locality	Pressure (GPa)	Temp (K)
0014561	Tweddillite	Armbruster T, Gnos E, Dixon R, Gutzmer J, Hejny C, Dobelin N, Medenbach O (2002) Manganvesuvianite and tweddillite, two new Mn3+-silicate minerals from the Kalahari manganese fields, South Africa Mineralogical Magazine 66 137-150		2002	Kalahari manganese fields, South Africa	0	293

CIF Raw Data - click here to close

X-Ray Powder DiffractionHide

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Powder Diffraction Data:

Type Occurrence of TweddilliteHide

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General Appearance of Type Material:

Dark-red ‘suns’ of very thin (~0.02 mm) radiating (001) blades, elongated parallel to [010] (up to 0.5 mm).

Place of Conservation of Type Material:

(NMBE 35475) at the Natural History Museum, Bern, Switzerland.

Geological Setting of Type Material:

In calcsilicate rocks formed as hydrothermal alteration of primary sedimentary manganese ore.

Associated Minerals at Type Locality:

Reference:

Armbruster, T., Gnos, E., Dixon, R., Gutzmer, J., Hejny, C., Döbelin, N., Medenbach, O. (2002) Manganvesuvianite and tweddillite, two new Mn3+-silicate minerals from the Kalahari Manganese fields, South Africa. Mineralogical Magazine: 66: 137-150.

Synonyms of TweddilliteHide

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Other Language Names for TweddilliteHide

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Relationship of Tweddillite to other SpeciesHide

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Other Members of this group:

Common AssociatesHide

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Associated Minerals Based on Photo Data:

Related Minerals - Strunz-mindat GroupingHide

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Other InformationHide

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Health Risks:

No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

Internet Links for TweddilliteHide

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References for TweddilliteHide

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Reference List:

Armbruster, T., Gnos, E., Dixon, R., Gutzmer, J., Hejny, C., Döbelin, N., Medenbach, O. (2002) Manganvesuvianite and tweddillite, two new Mn3+-silicate minerals from the Kalahari manganese fields, South Africa. Mineralogical Magazine, 66 (1) 137-150 doi:10.1180/0026461026610018

Armbruster, Thomas, Bonazzi, Paola, Akasaka, Masahide, Bermanec, Vladimir, Chopin, Christian, Gieré, Reto, Heuss-Assbichler, Soraya, Liebscher, Axel, Menchetti, Silvio, Pan, Yuanming, Pasero, Marco (2006) Recommended nomenclature of epidote-group minerals. European Journal of Mineralogy, 18 (5) 551-567 doi:10.1127/0935-1221/2006/0018-0551

Localities for TweddilliteHide

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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

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