Siwaqaite (original) (raw)

A valid IMA mineral species

About SiwaqaiteHide

This section is currently hidden. Click the show button to view.

Formula:

Ca6Al2(CrO4)3(OH)12 · 26H2O

Specific Gravity:

1.819 (Calculated)

Name:

Named for the Siwaqa area, Jordan, the type locality.

The Cr (chromate) analogue of ettringite. First chromate-dominant group member. First chromate mineral to combine Ca and Al.

The temperature of formation is not higher than ~70–80 °C, based on mineral association and inferred from the formation conditions of the natural and synthetic members of the ettringite group minerals, which are stable at conditions of T < 120 °C and pH = 9.5–13.

Unique IdentifiersHide

This section is currently hidden. Click the show button to view.

Long-form identifier:

mindat:1:1:53414:1

594aa3cb-2cee-4e8c-a7f6-a00aa900b0bf

IMA Classification of SiwaqaiteHide

This section is currently hidden. Click the show button to view.

Type description reference:

Juroszek, Rafał, Krüger, Biljana, Galuskina, Irina, Krüger, Hannes, Vapnik, Yevgeny, Galuskin, Evgeny (2020) Siwaqaite, Ca6Al2(CrO4)3(OH)12·26H2O, a new mineral of the ettringite group from the pyrometamorphic Daba-Siwaqa complex, Jordan. American Mineralogist, 105 (3) 409-421 doi:10.2138/am-2020-7208

Classification of SiwaqaiteHide

This section is currently hidden. Click the show button to view.

7.DG.15

7 : SULFATES (selenates, tellurates, chromates, molybdates, wolframates)
D : Sulfates (selenates, etc.) with additional anions, with H2O
G : With large and medium-sized cations; with NO3, CO3, B(OH)4, SiO4 or IO3

Mineral SymbolsHide

This section is currently hidden. Click the show button to view.

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

Physical Properties of SiwaqaiteHide

This section is currently hidden. Click the show button to view.

Comment:

Based on scratch tests; micro-hardness test could not be performed

Fracture:

Irregular/Uneven

Density:

1.819 g/cm3 (Calculated)

Comment:

Could not be measured

Optical Data of SiwaqaiteHide

This section is currently hidden. Click the show button to view.

RI values:

_n_ω = 1.512(2) _n_ε = 1.502(2)

δ = 0.010

Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.

Pleochroism:

Non-pleochroic

Chemistry of SiwaqaiteHide

This section is currently hidden. Click the show button to view.

Mindat Formula:

Ca6Al2(CrO4)3(OH)12 · 26H2O

Crystallography of SiwaqaiteHide

This section is currently hidden. Click the show button to view.

Class (H-M):

3_m_ - Ditrigonal Pyramidal

Cell Parameters:

a = 11.3640(2) Å, c = 21.4485(2) Å

Unit Cell V:

2,398.78 ų (Calculated from Unit Cell)

Morphology:

Hexagonal prisms, terminated by a pyramid or a pinacoid.

X-Ray Powder DiffractionHide

This section is currently hidden. Click the show button to view.

Powder Diffraction Data:

Geological EnvironmentHide

This section is currently hidden. Click the show button to view.

Type Occurrence of SiwaqaiteHide

This section is currently hidden. Click the show button to view.

General Appearance of Type Material:

Grain aggregates and hexagonal prismatic crystals up to 250 mm in size

Place of Conservation of Type Material:

Collections of the Fersman Mineralogical Museum, Russian Academy of Sciences, Leninskiy Prospekt 18-2, Moscow 119071, Russia, registration number 5277/1

Geological Setting of Type Material:

Thin veins and small cavities in spurrite marble

Associated Minerals at Type Locality:

Reference:

Juroszek, R., Krüger, B., Galuskina, I., Krüger, H., Vapnik, Y., Galuskin, E. (2020) Siwaqaite, Ca6Al2(CrO4)3(OH)12·26H2O, a new mineral of the ettringite group from the pyrometamorphic Daba-Siwaqa complex, Jordan. American Mineralogist: 105(3): 409–421.

Synonyms of SiwaqaiteHide

This section is currently hidden. Click the show button to view.

Relationship of Siwaqaite to other SpeciesHide

This section is currently hidden. Click the show button to view.

Other Members of this group:

Common AssociatesHide

This section is currently hidden. Click the show button to view.

Associated Minerals Based on Photo Data:

Related Minerals - Strunz-mindat GroupingHide

This section is currently hidden. Click the show button to view.

Other InformationHide

This section is currently hidden. Click the show button to view.

IR Spectrum:

Absorption bands at 3318 and 3620 cm-1 (O-H stretching), 1629 and 1650 cm-1 (bending vibration of water), 1108 and 540 cm-1 (asymmetric stretching and bending of (SO4)2-), 540 cm-1 (Al-OH bending vibrations), and 869 cm-1 (asymmetric stretching vibrations of (CrO4)2-).

Notes:

Dissolved in 10% HCl and loses color in ethanol at room temperature.

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 SiwaqaiteHide

This section is currently hidden. Click the show button to view.

References for SiwaqaiteHide

This section is currently hidden. Click the show button to view.

Reference List:

Juroszek, Rafał, Krüger, Biljana, Galuskina, Irina, Krüger, Hannes, Vapnik, Yevgeny, Galuskin, Evgeny (2020) Siwaqaite, Ca6Al2(CrO4)3(OH)12·26H2O, a new mineral of the ettringite group from the pyrometamorphic Daba-Siwaqa complex, Jordan. American Mineralogist, 105 (3) 409-421 doi:10.2138/am-2020-7208

Localities for SiwaqaiteHide

This section is currently hidden. Click the show button to view.

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 section is currently hidden. Click the show button to view.

- This locality has map coordinates listed. - This locality has estimated coordinates. ⓘ - Click for references and 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 (e.g. from pseudomorphs).

All localities listed without proper references should be considered as questionable.