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Silhouette Island, Seychellesi
Regional Level Types
Silhouette IslandIsland
SeychellesCountry

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Type:
Island
Age:
63.8 Ma
Geologic Time:
Paleocene
Dating method:
K-Ar
Reference for age:
Dickin, A. P., Fallick, A. E., Halliday, A. N., Macintyre, R. M., & Stephens, W. E. (1986). An isotopic and geochronological investigation of the younger igneous rocks of the Seychelles microcontinent. Earth and Planetary Science Letters, 81(1), 46-56. doi.org/10.1016/0012-821X(86)90099-3
Mindat Locality ID:
230405
Long-form identifier:
mindat:1:2:230405:5
GUID (UUID V4):
0
Other Languages:
View 14 more...
French:
Silhouette, Seychelles
German:
Silhouette, Seychellen
Italian:
Silhouette , Seychelles
Russian:
Силуэт, Сейшельские Острова
Simplified Chinese:
錫盧埃特島, 塞舌尔
Spanish:
Isla de Silhouette, Seychelles
Bulgarian:
Силхоуете, Сейшели
Cebuano:
Silhouette, Seychelles
Dutch:
Silhouette, Seychellen
Esperanto:
Silhouette, Sejŝeloj
Estonian:
Silhouette, Seišellid
Galician:
Silhouette, Seixeles
Georgian:
სილუეტი , სეიშელის კუნძულები
Hebrew:
אי הצללית, סיישל
Hungarian:
Silhouette-sziget, Seychelle-szigetek
Japanese:
シルエット島, セーシェル
Lithuanian:
Silueto sala, Seišeliai
Polish:
Silhouette, Seszele
Portuguese:
Ilha Silhouette, Seychelles
Ukrainian:
Силует, Сейшельські острови


Silhouette Island lies 20 km (12 mi) northwest of Mahé in the Seychelles. It is the third-largest granitic island in the Seychelles. It has an area of 20.1 km² and has a population of 200, mostly workers on the island on the Somali Sea. The main settlement is La Passe, where a Hilton Hotel is located. The name Silhouette was given after Étienne de Silhouette (1709-1767), the French minister of finances under Louis XV.

The island is mountainous with five peaks over 500 m (1,600 ft) in elevation; Mont Dauban 751 m (2,464 ft), Mont-Pot-a-Eau 621 m (2,037 ft), Gratte Fesse 515 m (1,690 ft), Mont Corgat 502 m (1,647 ft) and Mont Cocos Marrons 500 m (1,600 ft). As such, it has some of the most dramatic scenery of the islands.

Though superficially similar to neighbouring islands, much of Silhouette is made up of younger syenite dated from 63 million years ago. Between Point Ramasse Tout and Point Zeng Zeng lies the only surface volcanic ash in Seychelles.

The island of Silhouette is composed of a volcanic unit (trachytic tuff) and a composite syenite and riebeckite granite ring complex (Baker, 1963; Dickin et al., 1986; Stephens, 1996).

Select Mineral List Type

Standard Detailed Gallery Strunz Chemical Elements

Mineral List


9 valid minerals.

Rock Types Recorded

Note: data is currently VERY limited. Please bear with us while we work towards adding this information!

Select Rock List Type

Alphabetical List Tree Diagram

Detailed Mineral List:

ⓘ Aenigmatite
Formula: Na4[Fe2+10Ti2]O4[Si12O36]
ⓘ Arfvedsonite
Formula: [Na][Na2][Fe2+4Fe3+]Si8O22(OH)2
ⓘ Augite
Formula: (CaxMgyFez)(Mgy1Fez1)Si2O6
ⓘ 'Biotite'
Formula: K(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2
ⓘ Fayalite
Formula: Fe2+2SiO4
ⓘ Ferro-richterite
Formula: {Na}{CaNa}{Fe2+5}(Si8O22)(OH)2
ⓘ Gibbsite
Formula: Al(OH)3
ⓘ Hedenbergite
Formula: CaFe2+Si2O6
ⓘ 'Hornblende Root Name Group'
Formula: ◻Ca2(Z2+4Z3+)(AlSi7O22)(OH,F,Cl)2
ⓘ Kaolinite
Formula: Al2(Si2O5)(OH)4
ⓘ Riebeckite
Formula: ◻[Na2][Fe2+3Fe3+2]Si8O22(OH)2

Gallery:

List of minerals arranged by Strunz 10th Edition classification

Group 4 - Oxides and Hydroxides
ⓘGibbsite4.FE.10Al(OH)3
Group 9 - Silicates
ⓘFayalite9.AC.05Fe2+2SiO4
ⓘAugite9.DA.15(CaxMgyFez)(Mgy1Fez1)Si2O6
ⓘHedenbergite9.DA.15CaFe2+Si2O6
ⓘFerro-richterite9.DE.20{Na}{CaNa}{Fe2+5}(Si8O22)(OH)2
ⓘArfvedsonite9.DE.25[Na][Na2][Fe2+4Fe3+]Si8O22(OH)2
ⓘRiebeckite9.DE.25◻[Na2][Fe2+3Fe3+2]Si8O22(OH)2
ⓘAenigmatite9.DH.40Na4[Fe2+10Ti2]O4[Si12O36]
ⓘKaolinite9.ED.05Al2(Si2O5)(OH)4
Unclassified
ⓘ'Biotite'-K(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2
ⓘ'Hornblende Root Name Group'-◻Ca2(Z2+4Z3+)(AlSi7O22)(OH,F,Cl)2

List of minerals for each chemical element

HHydrogen
Hⓘ Arfvedsonite[Na][Na2][Fe42+Fe3+]Si8O22(OH)2
Hⓘ BiotiteK(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2
Hⓘ Ferro-richterite{Na}{CaNa}{Fe52+}(Si8O22)(OH)2
Hⓘ GibbsiteAl(OH)3
Hⓘ KaoliniteAl2(Si2O5)(OH)4
Hⓘ Riebeckite◻[Na2][Fe32+Fe23+]Si8O22(OH)2
Hⓘ Hornblende Root Name Group◻Ca2(Z42+Z3+)(AlSi7O22)(OH,F,Cl)2
OOxygen
Oⓘ AenigmatiteNa4[Fe102+Ti2]O4[Si12O36]
Oⓘ Arfvedsonite[Na][Na2][Fe42+Fe3+]Si8O22(OH)2
Oⓘ Augite(CaxMgyFez)(Mgy1Fez1)Si2O6
Oⓘ BiotiteK(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2
Oⓘ FayaliteFe22+SiO4
Oⓘ Ferro-richterite{Na}{CaNa}{Fe52+}(Si8O22)(OH)2
Oⓘ GibbsiteAl(OH)3
Oⓘ HedenbergiteCaFe2+Si2O6
Oⓘ KaoliniteAl2(Si2O5)(OH)4
Oⓘ Riebeckite◻[Na2][Fe32+Fe23+]Si8O22(OH)2
Oⓘ Hornblende Root Name Group◻Ca2(Z42+Z3+)(AlSi7O22)(OH,F,Cl)2
FFluorine
Fⓘ BiotiteK(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2
Fⓘ Hornblende Root Name Group◻Ca2(Z42+Z3+)(AlSi7O22)(OH,F,Cl)2
NaSodium
Naⓘ AenigmatiteNa4[Fe102+Ti2]O4[Si12O36]
Naⓘ Arfvedsonite[Na][Na2][Fe42+Fe3+]Si8O22(OH)2
Naⓘ Ferro-richterite{Na}{CaNa}{Fe52+}(Si8O22)(OH)2
Naⓘ Riebeckite◻[Na2][Fe32+Fe23+]Si8O22(OH)2
MgMagnesium
Mgⓘ Augite(CaxMgyFez)(Mgy1Fez1)Si2O6
Mgⓘ BiotiteK(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2
AlAluminium
Alⓘ BiotiteK(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2
Alⓘ GibbsiteAl(OH)3
Alⓘ KaoliniteAl2(Si2O5)(OH)4
Alⓘ Hornblende Root Name Group◻Ca2(Z42+Z3+)(AlSi7O22)(OH,F,Cl)2
SiSilicon
Siⓘ AenigmatiteNa4[Fe102+Ti2]O4[Si12O36]
Siⓘ Arfvedsonite[Na][Na2][Fe42+Fe3+]Si8O22(OH)2
Siⓘ Augite(CaxMgyFez)(Mgy1Fez1)Si2O6
Siⓘ BiotiteK(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2
Siⓘ FayaliteFe22+SiO4
Siⓘ Ferro-richterite{Na}{CaNa}{Fe52+}(Si8O22)(OH)2
Siⓘ HedenbergiteCaFe2+Si2O6
Siⓘ KaoliniteAl2(Si2O5)(OH)4
Siⓘ Riebeckite◻[Na2][Fe32+Fe23+]Si8O22(OH)2
Siⓘ Hornblende Root Name Group◻Ca2(Z42+Z3+)(AlSi7O22)(OH,F,Cl)2
ClChlorine
Clⓘ Hornblende Root Name Group◻Ca2(Z42+Z3+)(AlSi7O22)(OH,F,Cl)2
KPotassium
Kⓘ BiotiteK(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2
CaCalcium
Caⓘ Augite(CaxMgyFez)(Mgy1Fez1)Si2O6
Caⓘ Ferro-richterite{Na}{CaNa}{Fe52+}(Si8O22)(OH)2
Caⓘ HedenbergiteCaFe2+Si2O6
Caⓘ Hornblende Root Name Group◻Ca2(Z42+Z3+)(AlSi7O22)(OH,F,Cl)2
TiTitanium
Tiⓘ AenigmatiteNa4[Fe102+Ti2]O4[Si12O36]
Tiⓘ BiotiteK(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2
FeIron
Feⓘ AenigmatiteNa4[Fe102+Ti2]O4[Si12O36]
Feⓘ Arfvedsonite[Na][Na2][Fe42+Fe3+]Si8O22(OH)2
Feⓘ Augite(CaxMgyFez)(Mgy1Fez1)Si2O6
Feⓘ BiotiteK(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2
Feⓘ FayaliteFe22+SiO4
Feⓘ Ferro-richterite{Na}{CaNa}{Fe52+}(Si8O22)(OH)2
Feⓘ HedenbergiteCaFe2+Si2O6
Feⓘ Riebeckite◻[Na2][Fe32+Fe23+]Si8O22(OH)2

Fossils

This region is too big or complex to display the fossil list, try looking at smaller subregions.

Other Databases

Wikipedia:https://en.wikipedia.org/wiki/Silhouette_Island
Wikidata ID:Q40413
GeoNames ID:241163


This page contains all mineral locality references listed on mindat.org. This does not claim to be a complete list. If you know of more minerals from this site, please register so you can add to our database. This locality information is for reference purposes only. You should never attempt to visit any sites listed in mindat.org without first ensuring that you have the permission of the land and/or mineral rights holders for access and that you are aware of all safety precautions necessary.

References

Baker, B.H. (1963) Geology and mineral resources of the Seychelles Archipelago. Memoir No.3, Ministry of Commerce and Industry, Geological Survey of Kenya.
Dickin, A.P., Fallick, A.E., Halliday, A.N., Macintyre, R.M., Stephens, W.E. (1986) An isotopic and geochronological investigation of the younger igneous rocks of the Seychelles microcontinent. Earth and Planetary Science Letters, 81 (1) 46-56 doi:10.1016/0012-821x(86)90099-3
Stephens, W.E. (1996) Geology of Silhouette island. Phelsuma, 4. 11-18
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