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Arnhem Cave, Windhoek Rural, Khomas Region, Namibiai
Regional Level Types
Arnhem CaveCave
Windhoek RuralConstituency
Khomas RegionRegion
NamibiaCountry

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Key
Latitude & Longitude (WGS84):
23° 26' 59'' South , 18° 31' 59'' East
Latitude & Longitude (decimal):
Locality type:
Köppen climate type:


On Arnhem farm 222, 150 km east of Windhoek. 4,5 km long cave system. Mined for bat guano. A white friable slag with arnhemite, pyrocoproite and pyrophosphite (all three names published without IMA approval) is interpreted to have resulted from the melting of ashes during the combustion of bat guano.


Regions containing this locality

African PlateTectonic Plate

Select Mineral List Type

Standard Detailed Strunz Dana Chemical Elements

Mineral List


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

Detailed Mineral List:

Arcanite
Formula: K2SO4
Reference: Martini, J.E.J. (1992) Swaknoite [Ca(NH4)2·(HPO4)2·H2O, orthorhombic]: A new mineral from Arnhem cave, Namibia. Bulletin of the South African Speleological Association: 32: 72-74.
Archerite
Formula: (K,NH4)(H2PO4)
Reference: [AmMin 84:193]
'Arnhemite'
Formula: (K,Na)4Mg2(P2O7)2 · 5H2O
Reference: [South African Speleological Assoc.(1994) 33, 66-69; AmMin 84:193]
Cristobalite
Formula: SiO2
Reference: [AmMin 84:193]
Dittmarite
Formula: (NH4)Mg(PO4) · H2O
Reference: Martini, J.E.J. (1992) Swaknoite [Ca(NH4)2·(HPO4)2·H2O, orthorhombic]: A new mineral from Arnhem cave, Namibia. Bulletin of the South African Speleological Association: 32: 72-74.
Mundrabillaite
Formula: (NH4)2Ca(HPO4)2 · H2O
Reference: Martini, J.E.J. (1992) Swaknoite [Ca(NH4)2·(HPO4)2·H2O, orthorhombic]: A new mineral from Arnhem cave, Namibia. Bulletin of the South African Speleological Association: 32: 72-74.
'Pyrocoproite'
Formula: (K,Na)2Mg(P2O7)
Description: Considered a pre-cursor material for arnhemite.
Reference: [Proc.12th Int.Congr.Speleology, La Chaux de Fonds, Switzerland,97/233-235; AmMin 84:197]
'Pyrophosphite'
Formula: K2Ca(P2O7)
Reference: [Bull. South African Speleological Assoc.(1994) 33, 66-69; AmMin 84:193]
Quartz
Formula: SiO2
Reference: [AmMin 84:193]
Swaknoite (TL)
Formula: (NH4)2Ca(HPO4)2 · H2O
Type Locality:
Reference: Martini, J.E.J. (1992) Swaknoite [Ca(NH4)2·(HPO4)2·H2O, orthorhombic]: A new mineral from Arnhem cave, Namibia. Bulletin of the South African Speleological Association: 32: 72-74.

List of minerals arranged by Strunz 10th Edition classification

Group 4 - Oxides and Hydroxides
Cristobalite4.DA.15SiO2
Quartz4.DA.05SiO2
Group 7 - Sulphates, Chromates, Molybdates and Tungstates
Arcanite7.AD.05K2SO4
Group 8 - Phosphates, Arsenates and Vanadates
Archerite8.AD.15(K,NH4)(H2PO4)
'Arnhemite'8.FC.20(K,Na)4Mg2(P2O7)2 · 5H2O
Dittmarite8.CH.20(NH4)Mg(PO4) · H2O
Mundrabillaite8.CJ.10(NH4)2Ca(HPO4)2 · H2O
'Pyrocoproite'8.FA.20(K,Na)2Mg(P2O7)
'Pyrophosphite'8.FA.20K2Ca(P2O7)
Swaknoite (TL)8.CJ.10(NH4)2Ca(HPO4)2 · H2O

List of minerals arranged by Dana 8th Edition classification

Group 28 - ANHYDROUS ACID AND NORMAL SULFATES
A2XO4
Arcanite28.2.1.2K2SO4
Group 37 - ANHYDROUS ACID PHOSPHATES, ARSENATES AND VANADATES
Miscellaneous
Archerite37.1.4.2(K,NH4)(H2PO4)
Group 38 - ANHYDROUS NORMAL PHOSPHATES, ARSENATES, AND VANADATES
Miscellaneous
'Pyrophosphite'38.5.8.K2Ca(P2O7)
Group 39 - HYDRATED ACID PHOSPHATES,ARSENATES AND VANADATES
Miscellaneous
Mundrabillaite39.3.3.1(NH4)2Ca(HPO4)2 · H2O
Swaknoite (TL)39.3.4.1(NH4)2Ca(HPO4)2 · H2O
Group 40 - HYDRATED NORMAL PHOSPHATES,ARSENATES AND VANADATES
AB(XO4)·xH2O
Dittmarite40.1.2.1(NH4)Mg(PO4) · H2O
Group 75 - TECTOSILICATES Si Tetrahedral Frameworks
Si Tetrahedral Frameworks - SiO2 with [4] coordinated Si
Cristobalite75.1.1.1SiO2
Quartz75.1.3.1SiO2
Unclassified Minerals, Mixtures, etc.
'Arnhemite'-(K,Na)4Mg2(P2O7)2 · 5H2O
'Pyrocoproite'-(K,Na)2Mg(P2O7)

List of minerals for each chemical element

HHydrogen
H Swaknoite(NH4)2Ca(HPO4)2 · H2O
H Dittmarite(NH4)Mg(PO4) · H2O
H Mundrabillaite(NH4)2Ca(HPO4)2 · H2O
H Arnhemite(K,Na)4Mg2(P2O7)2 · 5H2O
H Archerite(K,NH4)(H2PO4)
NNitrogen
N Swaknoite(NH4)2Ca(HPO4)2 · H2O
N Dittmarite(NH4)Mg(PO4) · H2O
N Mundrabillaite(NH4)2Ca(HPO4)2 · H2O
OOxygen
O Swaknoite(NH4)2Ca(HPO4)2 · H2O
O ArcaniteK2SO4
O Dittmarite(NH4)Mg(PO4) · H2O
O Mundrabillaite(NH4)2Ca(HPO4)2 · H2O
O Arnhemite(K,Na)4Mg2(P2O7)2 · 5H2O
O PyrophosphiteK2Ca(P2O7)
O Archerite(K,NH4)(H2PO4)
O QuartzSiO2
O CristobaliteSiO2
O Pyrocoproite(K,Na)2Mg(P2O7)
NaSodium
Na Arnhemite(K,Na)4Mg2(P2O7)2 · 5H2O
Na Pyrocoproite(K,Na)2Mg(P2O7)
MgMagnesium
Mg Dittmarite(NH4)Mg(PO4) · H2O
Mg Arnhemite(K,Na)4Mg2(P2O7)2 · 5H2O
Mg Pyrocoproite(K,Na)2Mg(P2O7)
SiSilicon
Si QuartzSiO2
Si CristobaliteSiO2
PPhosphorus
P Swaknoite(NH4)2Ca(HPO4)2 · H2O
P Dittmarite(NH4)Mg(PO4) · H2O
P Mundrabillaite(NH4)2Ca(HPO4)2 · H2O
P Arnhemite(K,Na)4Mg2(P2O7)2 · 5H2O
P PyrophosphiteK2Ca(P2O7)
P Archerite(K,NH4)(H2PO4)
P Pyrocoproite(K,Na)2Mg(P2O7)
SSulfur
S ArcaniteK2SO4
KPotassium
K ArcaniteK2SO4
K Arnhemite(K,Na)4Mg2(P2O7)2 · 5H2O
K PyrophosphiteK2Ca(P2O7)
K Archerite(K,NH4)(H2PO4)
K Pyrocoproite(K,Na)2Mg(P2O7)
CaCalcium
Ca Swaknoite(NH4)2Ca(HPO4)2 · H2O
Ca Mundrabillaite(NH4)2Ca(HPO4)2 · H2O
Ca PyrophosphiteK2Ca(P2O7)

References

Sort by

Year (asc) Year (desc) Author (A-Z) Author (Z-A)
- Martini, J. E. (1994): Two new minerals originated from bat guano combustion in Arnhem Cave, Namibia. South African Speleological Assoc. Bull. 33, 66-69. [Abstract in Am. Mineral. 84, 193]
- Bezing, L. von, Bode, R. & Jahn, S. (2008): Namibia Minerals and Localities. Edition Schloss Freudenstein, Bode Verlag GmbH, Haltern, 455 pp. (in English)


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