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Letseng-La-Terae Mine (Letseng Mine; Lets'eng Mine), Maluti Mts., Mokhotlong District, Lesothoi
Regional Level Types
Letseng-La-Terae Mine (Letseng Mine; Lets'eng Mine)Mine
Maluti Mts.- not defined -
Mokhotlong DistrictDistrict
LesothoCountry

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Key
Lock Map
Latitude & Longitude (WGS84): 29° 0' 17'' South , 28° 51' 38'' East
Latitude & Longitude (decimal): -29.00489,28.86083
GeoHash:G#: kdudbxzf6
Locality type:Mine
Köppen climate type:Cwb : Subtropical highland climate or temperate oceanic climate with dry winters
Nearest Settlements:
PlacePopulationDistance
Mokhotlong8,809 (2010)37.4km


A diamond mine, currently owned by African Gem Diamonds. The deposit consists of several kimberlite pipes intruded through 1500 m of Karoo (Stormberg) basalt. Two of the pipes, referred to as the Main and Satellite pipes respectively, have economic grades. They were discovered in 1957 as a weathered outcrop in a stream. In 1959, it was declared a "government digging" and hundreds of small-scale miners started to excavate the near-surface weathered kimberlite. In 1968, the property was acquired by Rio Tinto and explored through a series of underground tunnels, but the prospect was abandoned in 1972. De Beers subsequently acquired the deposit and mined the Main Pipe from 1975 until 1982. During this time, only little work was done on the Satellite Pipe. In 1999, the mining rights were obtained by Letseng Diamonds, who focussed their activities on the Satellite Pipe. In 2007, the mine was aquired by African Gem Diamonds.

During mining operations in the Satellite Pipe, a high number of large diamonds of exceptional quality were recovered, among them stones of 72, 76, 106 and 112 carats within a single week. The 603 ct "Lesotho Promise", discovered in 2006, ranks as the world's 15th largest diamond. It is said that 15% of the production is larger than 10 carats, and 1% is larger than 100 carats, per stone.

The Letseng pipes also contain abundant mantle and lower crustal xenoliths, including garnet-bearing gneisses and granulites, eclogites, lherzolites, harzburgites and dunites.

A 494-carat diamond, believed to be the 18th largest in the world, has been found at this mine in Lesotho.

The stone was an exceptional quality white diamond, said Natural Resources Minister Monyane Moleleki. "This recovery adds more to the chapter of excellence for this mine internationally," said a visibly elated Moleleki.

The Lesotho Promise, a 603-carat stone, was uncovered last year (2006) at the same mine and sold for $12.3 million. A 215-carat flawless diamond found in January 2007 brought $8.3 million.


A 910 caret diamond, the fifth largest ever discovered and as big as 2 golf balls, was found here as reported on January 15, 2018. It has been speculated that it may be worth as much as $40,000,000.

Regions containing this locality

Somali Plate (Somalia Plate)Tectonic Plate

Select Mineral List Type

Standard Detailed Strunz Dana Chemical Elements

Commodity List

This is a list of exploitable or exploited mineral commodities recorded at this locality.


Mineral List


8 valid minerals. 1 (TL) - type locality of valid minerals. 1 erroneous literature entry.

Detailed Mineral List:

'Albite-Anorthite Series'
Reference: Mineralogical Magazine (1980), 43, 583-586
'Apophyllite'
Reference: Bruce Cairncross photo ID 728843
Calcite
Formula: CaCO3
Reference: Mineralogical Magazine (1980), 43, 583-586
Cebollite
Formula: Ca5Al2(SiO4)3(OH)4
Description: In zeolitized plagioclase-rich gneiss, amphibolite, and basalt xenoliths in kimberlite. Pectolite
Reference: Mineralogical Magazine (1980), 43, 583-586; Dana VIII; F. J. Kruger (1982) The Occurrence of Cebollite in Kimberlite and Included Zeolitized Crustal Xenoliths—A Correction and Discussion of the Occurrence of Pectolite. Mineralogical Magazine 46:274-275.
Crowningshieldite (TL)
Formula: (Ni0.9Fe0.10)S
Type Locality:
Reference: Smith, E.M., Nestola, F., Pasqualetto, L., Zorzi, F., Secco, L. and Wang, W. (2018) Crowningshieldite, IMA 2018-072. CNMNC Newsletter No. 45, October 2018, page xxx; Mineralogical Magazine, 82, xxx-xxx.
Diamond
Formula: C
Reference: Field, M., Stiefenhofer, J., Robey, J., and Kurszlaukis, S. (2008): Ore Geology Reviews 34, 33-75.
Diopside
Formula: CaMgSi2O6
Reference: Field, M., Stiefenhofer, J., Robey, J., and Kurszlaukis, S. (2008): Ore Geology Reviews 34, 33-75.
Enstatite
Formula: MgSiO3
Reference: Field, M., Stiefenhofer, J., Robey, J., and Kurszlaukis, S. (2008): Ore Geology Reviews 34, 33-75.
Enstatite var: Bronzite
Formula: (Mg,Fe2+)2[SiO3]2
Reference: Field, M., Stiefenhofer, J., Robey, J., and Kurszlaukis, S. (2008): Ore Geology Reviews 34, 33-75.
'Fayalite-Forsterite Series'
Reference: Field, M., Stiefenhofer, J., Robey, J., and Kurszlaukis, S. (2008): Ore Geology Reviews 34, 33-75.
'Garnet Group'
Formula: X3Z2(SiO4)3
Reference: Field, M., Stiefenhofer, J., Robey, J., and Kurszlaukis, S. (2008): Ore Geology Reviews 34, 33-75.
Natrolite
Formula: Na2Al2Si3O10 · 2H2O
Reference: Mineralogical Magazine (1980), 43, 583-586
Pectolite
Formula: NaCa2Si3O8(OH)
Reference: F. J. Kruger (1982) The Occurrence of Cebollite in Kimberlite and Included Zeolitized Crustal Xenoliths—A Correction and Discussion of the Occurrence of Pectolite. Mineralogical Magazine 46:274-275.
Periclase
Formula: MgO
Reference: Field, M., Stiefenhofer, J., Robey, J., and Kurszlaukis, S. (2008): Ore Geology Reviews 34, 33-75.
Periclase var: Ferropericlase
Formula: (Mg,Fe)O
Reference: Field, M., Stiefenhofer, J., Robey, J., and Kurszlaukis, S. (2008): Ore Geology Reviews 34, 33-75.

List of minerals arranged by Strunz 10th Edition classification

Group 1 - Elements
Diamond1.CB.10aC
Group 4 - Oxides and Hydroxides
Periclase4.AB.25MgO
var: Ferropericlase4.AB.25(Mg,Fe)O
Group 5 - Nitrates and Carbonates
Calcite5.AB.05CaCO3
Group 9 - Silicates
Cebollite ?9.BB.10Ca5Al2(SiO4)3(OH)4
Diopside9.DA.15CaMgSi2O6
Enstatite9.DA.05MgSiO3
var: Bronzite9.DA.05(Mg,Fe2+)2[SiO3]2
Natrolite9.GA.05Na2Al2Si3O10 · 2H2O
Pectolite9.DG.05NaCa2Si3O8(OH)
Unclassified Minerals, Rocks, etc.
'Albite-Anorthite Series'-
'Apophyllite'-
Crowningshieldite (TL)-(Ni0.9Fe0.10)S
'Fayalite-Forsterite Series'-
'Garnet Group'-X3Z2(SiO4)3

List of minerals arranged by Dana 8th Edition classification

Group 1 - NATIVE ELEMENTS AND ALLOYS
Semi-metals and non-metals
Diamond1.3.6.1C
Group 4 - SIMPLE OXIDES
AX
Periclase4.2.1.1MgO
Group 14 - ANHYDROUS NORMAL CARBONATES
A(XO3)
Calcite14.1.1.1CaCO3
Group 65 - INOSILICATES Single-Width,Unbranched Chains,(W=1)
Single-Width Unbranched Chains, W=1 with chains P=2
Diopside65.1.3a.1CaMgSi2O6
Enstatite65.1.2.1MgSiO3
Single-Width Unbranched Chains, W=1 with chains P=3
Pectolite65.2.1.4aNaCa2Si3O8(OH)
Group 77 - TECTOSILICATES Zeolites
Zeolite group - True zeolites
Natrolite77.1.5.1Na2Al2Si3O10 · 2H2O
Group 78 - Unclassified Silicates
Miscellaneous
Cebollite ?78.1.1.1Ca5Al2(SiO4)3(OH)4
Unclassified Minerals, Mixtures, etc.
'Albite-Anorthite Series'-
'Apophyllite'-
Crowningshieldite (TL)-(Ni0.9Fe0.10)S
Enstatite
var: Bronzite
-(Mg,Fe2+)2[SiO3]2
'Fayalite-Forsterite Series'-
'Garnet Group'-X3Z2(SiO4)3
Periclase
var: Ferropericlase
-(Mg,Fe)O

List of minerals for each chemical element

HHydrogen
H NatroliteNa2Al2Si3O10 · 2H2O
H PectoliteNaCa2Si3O8(OH)
H CebolliteCa5Al2(SiO4)3(OH)4
CCarbon
C DiamondC
C CalciteCaCO3
OOxygen
O CalciteCaCO3
O NatroliteNa2Al2Si3O10 · 2H2O
O Garnet GroupX3Z2(SiO4)3
O EnstatiteMgSiO3
O Enstatite (var: Bronzite)(Mg,Fe2+)2[SiO3]2
O DiopsideCaMgSi2O6
O Periclase (var: Ferropericlase)(Mg,Fe)O
O PectoliteNaCa2Si3O8(OH)
O PericlaseMgO
O CebolliteCa5Al2(SiO4)3(OH)4
NaSodium
Na NatroliteNa2Al2Si3O10 · 2H2O
Na PectoliteNaCa2Si3O8(OH)
MgMagnesium
Mg EnstatiteMgSiO3
Mg Enstatite (var: Bronzite)(Mg,Fe2+)2[SiO3]2
Mg DiopsideCaMgSi2O6
Mg Periclase (var: Ferropericlase)(Mg,Fe)O
Mg PericlaseMgO
AlAluminium
Al NatroliteNa2Al2Si3O10 · 2H2O
Al CebolliteCa5Al2(SiO4)3(OH)4
SiSilicon
Si NatroliteNa2Al2Si3O10 · 2H2O
Si Garnet GroupX3Z2(SiO4)3
Si EnstatiteMgSiO3
Si Enstatite (var: Bronzite)(Mg,Fe2+)2[SiO3]2
Si DiopsideCaMgSi2O6
Si PectoliteNaCa2Si3O8(OH)
Si CebolliteCa5Al2(SiO4)3(OH)4
SSulfur
S Crowningshieldite(Ni0.9Fe0.10)S
CaCalcium
Ca CalciteCaCO3
Ca DiopsideCaMgSi2O6
Ca PectoliteNaCa2Si3O8(OH)
Ca CebolliteCa5Al2(SiO4)3(OH)4
FeIron
Fe Crowningshieldite(Ni0.9Fe0.10)S
Fe Enstatite (var: Bronzite)(Mg,Fe2+)2[SiO3]2
Fe Periclase (var: Ferropericlase)(Mg,Fe)O
NiNickel
Ni Crowningshieldite(Ni0.9Fe0.10)S

Regional Geology

This geological map and associated information on rock units at or nearby to the coordinates given for this locality is based on relatively small scale geological maps provided by various national Geological Surveys. This does not necessarily represent the complete geology at this locality but it gives a background for the region in which it is found.

Click on geological units on the map for more information. Click here to view full-screen map on Macrostrat.org

Jurassic
145 - 201.3 Ma



ID: 2232428
Drakensberg Group of Karoo Supergroup

Age: Jurassic (145 - 201.3 Ma)

Stratigraphic Name: Drakensberg Group

Description: Basaltic lava, with minor sandstone, tuff and agglomerate in the lower part of the succession in places

Reference: Council for Geoscience. Geologic map of South Africa, 1:1M. National Science Councils of South Africa. [41]

Jurassic
145 - 201.3 Ma



ID: 3190897
Mesozoic volcanic rocks

Age: Jurassic (145 - 201.3 Ma)

Stratigraphic Name: Karoo Flood Basalt

Comments: Karoo Basin

Lithology: Mafic volcanic rocks

Reference: Chorlton, L.B. Generalized geology of the world: bedrock domains and major faults in GIS format: a small-scale world geology map with an extended geological attribute database. doi: 10.4095/223767. Geological Survey of Canada, Open File 5529. [154]

Jurassic
145 - 201.3 Ma



ID: 3311936

Age: Jurassic (145 - 201.3 Ma)

Lithology: Volcanic

Reference: Thiéblemont, D. (ed.). New edition of the 1:10,000,000 geological map of Africa. CGMW-BRGM. [190]

Data and map coding provided by Macrostrat.org, used under Creative Commons Attribution 4.0 License

References

Sort by

Year (asc) Year (desc) Author (A-Z) Author (Z-A)
Thakalekoala, Thabo (2007), Associated Press (September 13, 2007).
Field, M., Stiefenhofer, J., Robey, J., and Kurszlaukis, S. (2008): Kimberlite-hosted diamond deposits of southern Africa: A review. Ore Geology Reviews: 34: 33-75.

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