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Ascension Island, Saint Helenai
Regional Level Types
Ascension IslandIsland
Saint HelenaOverseas Territory

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Key
Area:
88 km2
Locality type:


An island in the Southern Atlantic Ocean, administered by the United Kingdom and having an area of 98 square kilometres.

Ascension is unusual among oceanic islands in having a high proportion of pyroclastic deposits relative to lava flows (approximately 40:60 based on exposure).

The central and eastern parts of the island predominantly comprise pyroclastic deposits (both mafic and silicic) and trachyte lava flows and domes.

The rest of the island predominantly comprises scoria cones and mafic lava flows, some of which have a thin veneer of pyroclastic deposits.

Select Mineral List Type

Standard Detailed Strunz Dana Chemical Elements

Mineral List

Mineral list contains entries from the region specified including sub-localities

13 valid minerals. 1 (TL) - type locality of valid minerals.

Rock Types Recorded

Note: this is a very new system on mindat.org and data is currently VERY limited. Please bear with us while we work towards adding this information!

Rock list contains entries from the region specified including sub-localities

Select Rock List Type

Alphabetical List Tree Diagram

Detailed Mineral List:

Aegirine
Formula: NaFe3+Si2O6
Aenigmatite
Formula: Na4[Fe2+10Ti2]O4[Si12O36]
'Alkali Feldspar'
'Amphibole Supergroup'
Formula: AX2Z5((Si,Al,Ti)8O22)(OH,F,Cl,O)2
Reference: Van Tassel, R. [ with a microchemical analysis by Hey, M.H.] (1952): Dalyite, a new potassium zirconium silicate from Ascension Island, Atlantic. Mineralogical Magazine, 29, 850-857.
'Apatite'
Formula: Ca5(PO4)3(Cl/F/OH)
Reference: American Mineralogist 28:215-232
'Apatite var: Collophane'
Reference: Richard, G. (1928): Newberyite and other phosphates from Ascension Island. Am. Mineral. 13, 397-401.; Palache, C., Berman, H., & Frondel, C. (1951), The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana, Yale University 1837-1892, Volume II: 710.
Arfvedsonite
Formula: [Na][Na2][Fe2+4Fe3+]Si8O22(OH)2
Dalyite (TL)
Formula: K2ZrSi6O15
Description: Accessory in ejected blocks of alkalic granite in trachytic and basaltic tuffs.
Reference: Van Tassel, R. [ with a microchemical analysis by Hey, M.H.] (1952): Dalyite, a new potassium zirconium silicate from Ascension Island, Atlantic. Mineralogical Magazine, 29, 850-857. Fleet, S.G. (1965): The crystal structure of dalyite. Zeitschrift für Krystallographie, 121, 349-368.
Eudialyte
Formula: Na15Ca6(Fe2+,Mn2+)3Zr3[Si25O73](O,OH,H2O)3(OH,Cl)2
Reference: C. Harris, G. Cressey, J. D. Bell, F. B. Atkins and S. Beswetherick (1982) An Occurrence of Rare-Earth-Rich Eudialyte from Ascension Island, South Atlantic. Mineralogical Magazine 46:421-425.
Fayalite
Formula: Fe2+2SiO4
Reference: C. Harris, G. Cressey, J. D. Bell, F. B. Atkins and S. Beswetherick (1982) An Occurrence of Rare-Earth-Rich Eudialyte from Ascension Island, South Atlantic. Mineralogical Magazine 46:421-425.
'Feldspar Group'
Reference: C. Harris, G. Cressey, J. D. Bell, F. B. Atkins and S. Beswetherick (1982) An Occurrence of Rare-Earth-Rich Eudialyte from Ascension Island, South Atlantic. Mineralogical Magazine 46:421-425.
'Feldspar Group var: Perthite'
Reference: C. Harris, G. Cressey, J. D. Bell, F. B. Atkins and S. Beswetherick (1982) An Occurrence of Rare-Earth-Rich Eudialyte from Ascension Island, South Atlantic. Mineralogical Magazine 46:421-425.
Hematite
Formula: Fe2O3
Reference: Richard Dale collection; Sunagawa, I. (1962) Mechanism of natural etching on hematite crystals. American Mineralogist, 47, 1332-1345.
Monetite
Formula: Ca(HPO4)
Reference: American Mineralogist 28:215-232
Newberyite
Formula: Mg(HPO4) · 3H2O
Reference: Richard, G. (1928): Newberyite and other phosphates from Ascension Island. Am. Mineral. 13, 397-401.; Palache, C., Berman, H., & Frondel, C. (1951), The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana, Yale University 1837-1892, Volume II: 710.; American Mineralogist 28:215-232
Quartz
Formula: SiO2
Vlasovite
Formula: Na2ZrSi4O11
Reference: http://rruff.geo.arizona.edu/doclib/mm/vol36/MM36_233.pdf
Whitlockite
Formula: Ca9Mg(PO4)6(HPO4)
Reference: Richard, G. (1928): Newberyite and other phosphates from Ascension Island. Am. Mineral. 13, 397-401.; American Mineralogist 28:215-232
Whitlockite var: Martinite (of Kloos)
Reference: Richard, G. (1928): Newberyite and other phosphates from Ascension Island. Am. Mineral. 13, 397-401.; American Mineralogist 28:215-232
Zircon
Formula: Zr(SiO4)
Reference: C. Harris, G. Cressey, J. D. Bell, F. B. Atkins and S. Beswetherick (1982) An Occurrence of Rare-Earth-Rich Eudialyte from Ascension Island, South Atlantic. Mineralogical Magazine 46:421-425.

List of minerals arranged by Strunz 10th Edition classification

Group 4 - Oxides and Hydroxides
Hematite4.CB.05Fe2O3
Quartz4.DA.05SiO2
Group 8 - Phosphates, Arsenates and Vanadates
Monetite8.AD.10Ca(HPO4)
Newberyite8.CE.10Mg(HPO4) · 3H2O
Whitlockite8.AC.45Ca9Mg(PO4)6(HPO4)
var: Martinite (of Kloos)8.AC.45Ca9Mg(PO4)6(HPO4)
Group 9 - Silicates
Aegirine9.DA.25NaFe3+Si2O6
Aenigmatite9.DH.40Na4[Fe2+10Ti2]O4[Si12O36]
Arfvedsonite9.DE.25[Na][Na2][Fe2+4Fe3+]Si8O22(OH)2
Dalyite (TL)9.EA.25K2ZrSi6O15
Eudialyte9.CO.10Na15Ca6(Fe2+,Mn2+)3Zr3[Si25O73](O,OH,H2O)3(OH,Cl)2
Fayalite9.AC.05Fe2+2SiO4
Vlasovite9.DM.25Na2ZrSi4O11
Zircon9.AD.30Zr(SiO4)
Unclassified Minerals, Rocks, etc.
'Alkali Feldspar'-
'Amphibole Supergroup'-AX2Z5((Si,Al,Ti)8O22)(OH,F,Cl,O)2
'Apatite'-Ca5(PO4)3(Cl/F/OH)
'var: Collophane'-Ca5(PO4)3(Cl/F/OH)
'Feldspar Group'-
'var: Perthite'-

List of minerals arranged by Dana 8th Edition classification

Group 4 - SIMPLE OXIDES
A2X3
Hematite4.3.1.2Fe2O3
Group 37 - ANHYDROUS ACID PHOSPHATES, ARSENATES AND VANADATES
Miscellaneous
Monetite37.1.1.1Ca(HPO4)
Group 38 - ANHYDROUS NORMAL PHOSPHATES, ARSENATES, AND VANADATES
(AB)3(XO4)2
Whitlockite38.3.4.1Ca9Mg(PO4)6(HPO4)
Group 39 - HYDRATED ACID PHOSPHATES,ARSENATES AND VANADATES
A[HXO4]·xH2O
Newberyite39.1.6.1Mg(HPO4) · 3H2O
Group 51 - NESOSILICATES Insular SiO4 Groups Only
Insular SiO4 Groups Only with all cations in octahedral [6] coordination
Fayalite51.3.1.1Fe2+2SiO4
Insular SiO4 Groups Only with cations in >[6] coordination
Zircon51.5.2.1Zr(SiO4)
Group 64 - CYCLOSILICATES Rings with Other Anions and Insular Silicate Groups
Rings with Other Anions and Insular Silicate Groups with mixed ring types
Eudialyte64.1.1.1Na15Ca6(Fe2+,Mn2+)3Zr3[Si25O73](O,OH,H2O)3(OH,Cl)2
Group 65 - INOSILICATES Single-Width,Unbranched Chains,(W=1)
Single-Width Unbranched Chains, W=1 with chains P=2
Aegirine65.1.3c.2NaFe3+Si2O6
Group 66 - INOSILICATES Double-Width,Unbranched Chains,(W=2)
Amphiboles - Ca subgroup
Vlasovite66.2.2.1Na2ZrSi4O11
Group 69 - INOSILICATES Chains with Side Branches or Loops
Chains with Side Branches or Loops with P>2
Aenigmatite69.2.1a.1Na4[Fe2+10Ti2]O4[Si12O36]
Group 72 - PHYLLOSILICATES Two-Dimensional Infinite Sheets with Other Than Six-Membered Rings
Two-Dimensional Infinite Sheets with Other Than Six-Membered Rings with 4-, 6-, and 8-membered rings
Dalyite (TL)72.2.1.1K2ZrSi6O15
Group 75 - TECTOSILICATES Si Tetrahedral Frameworks
Si Tetrahedral Frameworks - SiO2 with [4] coordinated Si
Quartz75.1.3.1SiO2
Unclassified Minerals, Mixtures, etc.
'Alkali Feldspar'-
'Amphibole Supergroup'-AX2Z5((Si,Al,Ti)8O22)(OH,F,Cl,O)2
'Apatite'-Ca5(PO4)3(Cl/F/OH)
'var: Collophane'-Ca5(PO4)3(Cl/F/OH)
Arfvedsonite-[Na][Na2][Fe2+4Fe3+]Si8O22(OH)2
'Feldspar Group'-
'var: Perthite'-
Whitlockite
var: Martinite (of Kloos)
-Ca9Mg(PO4)6(HPO4)

List of minerals for each chemical element

HHydrogen
H MonetiteCa(HPO4)
H Amphibole SupergroupAX2Z5((Si,Al,Ti)8O22)(OH,F,Cl,O)2
H Arfvedsonite[Na][Na2][Fe42+Fe3+]Si8O22(OH)2
H NewberyiteMg(HPO4) · 3H2O
H ApatiteCa5(PO4)3(Cl/F/OH)
H EudialyteNa15Ca6(Fe2+,Mn2+)3Zr3[Si25O73](O,OH,H2O)3(OH,Cl)2
H WhitlockiteCa9Mg(PO4)6(HPO4)
OOxygen
O DalyiteK2ZrSi6O15
O MonetiteCa(HPO4)
O AegirineNaFe3+Si2O6
O Amphibole SupergroupAX2Z5((Si,Al,Ti)8O22)(OH,F,Cl,O)2
O QuartzSiO2
O VlasoviteNa2ZrSi4O11
O Arfvedsonite[Na][Na2][Fe42+Fe3+]Si8O22(OH)2
O AenigmatiteNa4[Fe102+Ti2]O4[Si12O36]
O NewberyiteMg(HPO4) · 3H2O
O HematiteFe2O3
O ApatiteCa5(PO4)3(Cl/F/OH)
O EudialyteNa15Ca6(Fe2+,Mn2+)3Zr3[Si25O73](O,OH,H2O)3(OH,Cl)2
O FayaliteFe22+SiO4
O ZirconZr(SiO4)
O WhitlockiteCa9Mg(PO4)6(HPO4)
FFluorine
F Amphibole SupergroupAX2Z5((Si,Al,Ti)8O22)(OH,F,Cl,O)2
F ApatiteCa5(PO4)3(Cl/F/OH)
NaSodium
Na AegirineNaFe3+Si2O6
Na VlasoviteNa2ZrSi4O11
Na Arfvedsonite[Na][Na2][Fe42+Fe3+]Si8O22(OH)2
Na AenigmatiteNa4[Fe102+Ti2]O4[Si12O36]
Na EudialyteNa15Ca6(Fe2+,Mn2+)3Zr3[Si25O73](O,OH,H2O)3(OH,Cl)2
MgMagnesium
Mg NewberyiteMg(HPO4) · 3H2O
Mg WhitlockiteCa9Mg(PO4)6(HPO4)
AlAluminium
Al Amphibole SupergroupAX2Z5((Si,Al,Ti)8O22)(OH,F,Cl,O)2
SiSilicon
Si DalyiteK2ZrSi6O15
Si AegirineNaFe3+Si2O6
Si Amphibole SupergroupAX2Z5((Si,Al,Ti)8O22)(OH,F,Cl,O)2
Si QuartzSiO2
Si VlasoviteNa2ZrSi4O11
Si Arfvedsonite[Na][Na2][Fe42+Fe3+]Si8O22(OH)2
Si AenigmatiteNa4[Fe102+Ti2]O4[Si12O36]
Si EudialyteNa15Ca6(Fe2+,Mn2+)3Zr3[Si25O73](O,OH,H2O)3(OH,Cl)2
Si FayaliteFe22+SiO4
Si ZirconZr(SiO4)
PPhosphorus
P MonetiteCa(HPO4)
P NewberyiteMg(HPO4) · 3H2O
P ApatiteCa5(PO4)3(Cl/F/OH)
P WhitlockiteCa9Mg(PO4)6(HPO4)
ClChlorine
Cl Amphibole SupergroupAX2Z5((Si,Al,Ti)8O22)(OH,F,Cl,O)2
Cl ApatiteCa5(PO4)3(Cl/F/OH)
Cl EudialyteNa15Ca6(Fe2+,Mn2+)3Zr3[Si25O73](O,OH,H2O)3(OH,Cl)2
KPotassium
K DalyiteK2ZrSi6O15
CaCalcium
Ca MonetiteCa(HPO4)
Ca ApatiteCa5(PO4)3(Cl/F/OH)
Ca EudialyteNa15Ca6(Fe2+,Mn2+)3Zr3[Si25O73](O,OH,H2O)3(OH,Cl)2
Ca WhitlockiteCa9Mg(PO4)6(HPO4)
TiTitanium
Ti Amphibole SupergroupAX2Z5((Si,Al,Ti)8O22)(OH,F,Cl,O)2
Ti AenigmatiteNa4[Fe102+Ti2]O4[Si12O36]
MnManganese
Mn EudialyteNa15Ca6(Fe2+,Mn2+)3Zr3[Si25O73](O,OH,H2O)3(OH,Cl)2
FeIron
Fe AegirineNaFe3+Si2O6
Fe Arfvedsonite[Na][Na2][Fe42+Fe3+]Si8O22(OH)2
Fe AenigmatiteNa4[Fe102+Ti2]O4[Si12O36]
Fe HematiteFe2O3
Fe EudialyteNa15Ca6(Fe2+,Mn2+)3Zr3[Si25O73](O,OH,H2O)3(OH,Cl)2
Fe FayaliteFe22+SiO4
ZrZirconium
Zr DalyiteK2ZrSi6O15
Zr VlasoviteNa2ZrSi4O11
Zr EudialyteNa15Ca6(Fe2+,Mn2+)3Zr3[Si25O73](O,OH,H2O)3(OH,Cl)2
Zr ZirconZr(SiO4)

References

Sort by

Year (asc) Year (desc) Author (A-Z) Author (Z-A)
Darwin, C. (1876) Geological observations on the volcanic islands. 2nd Edition. Smith, Elder and Co., London, 674 pages.
Daly, R.A. (1925) The geology of Ascension Island. Proceedings of the American Academy of Arts and Sciences, 60, 1-80.
van Tassel, R. (1952) Dalyite, a new potassium zirconium silicate, from Ascension Island, Atlantic. Mineralogical Magazine, 29, 850-857.
Atkins, F.B., Baker, P.E., Bell, J.D., Smith, D.G.W. (1964) Oxford expedition to Ascension Island, 1964. Nature, 204, 722-724.
Gast, P.W., Tilton, G.R., Hedge, C. (1964) Isotopic composition of lead and strontium from Ascension and Gough islands. Science, 145, 1181-1185.
Roedder, E., Coombs, D.S. (1967) Immiscibility in granitic melts, indicated by fluid inclusions in ejected granitic blocks from Ascension Island. Journal of Petrology, 8, 417-451.
Harris, C., Bell, J.D. (1982) Natural partial melting of syenite blocks from Ascension Island. Contributions to Mineralogy and Petrology, 79, 107-113.
Harris, C., Bell, J.D., Atkins, F.B. (1982) Isotopic composition of lead and strontium in lavas and coarse-grained blocks from Ascension Island, South Atlantic. Earth and Planetary Science Letters, 60, 79-85.
Harris, C. (1983) The petrology of lavas and associated plutonic inclusions of Ascension Island. Journal of Petrology, 24, 424-470.
Weis, D. (1983) Pb isotopes in Ascension Island rocks: Oceanic origin for the gabbroic to granitic plutonic inclusions. Earth and Planetary Science Letters, 62, 273-282.
Harris, C. (1985) Guano-derived rare earth-rich phosphatic amygdales in gabbroic inclusions from Ascension Island. Earth and Planetary Science Letters, 72, 141-148.
Sheppard, S.M.F., Harris, C. (1985) Hydrogen and oxygen isotope geochemistry of Ascension Island lavas and granites: Variation with crystal fractionation and interaction with sea water. Contributions to Mineralogy and Petrology, 91, 74-81.
Harris, C., Sheppard, S.M.F. (1987) Magma and fluid evolution in the lavas and associated granite xenoliths of Ascension Island. In: Alkaline Igneous Rocks (Fitton, J.G., Upton, B.G.J. eds.), Geological Society of London Special Publication 30, 269-272.
Weaver, B.L., Wood, D.A., Tarney, J., Joron, J.-L. (1987) Geochemistry of ocean island basalts from the South Atlantic Ocean: Ascension, Bouvet, St. Helena, Gough and Tristan da Cunha. In: Alkaline Igneous Rocks (Fitton, J.G., Upton, B.G.J. eds.), Geological Society of London Special Publication 30, 253-267.
Weis, D., Demaiffe, D., Cauet, S., Javoy, M. (1987) Sr, Nd, O and H isotopic ratios in Ascension Island lavas and plutonic inclusions; cogenetic origin. Earth and Planetary Science Letters, 82, 255-268.
Weaver, B.L., Kar, A., Davidson, J., Colucci, M. (1996) Geochemical characteristics of volcanic rocks from Ascension Island, South Atlantic Ocean. Geothermics, 25, 449-470.
Kar, A., Weaver, B.L., Davidson, J., Colucci, M. (1998) Origin of differentiated volcanic and plutonic rocks from Ascension Island, South Atlantic Ocean. Journal of Petrology, 39, 1009-1024.

Other Databases

Wikipedia:https://en.wikipedia.org/wiki/Ascension_Island
Wikidata ID:Q46197

Localities in this Region

Other Regions, Features and Areas that Intersect

Atlantic Ocean
South America PlateTectonic Plate

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