Antetezambato Demantoid-Topazolite Mine, Antsakoamanondro, Ambanja, Diana, Madagascari
| Regional Level Types | |
|---|---|
| Antetezambato Demantoid-Topazolite Mine | Mining Field |
| Antsakoamanondro | Commune |
| Ambanja | District |
| Diana | Region |
| Madagascar | Country |
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Latitude & Longitude (WGS84):
13° 30' 0'' South , 48° 31' 59'' East
Latitude & Longitude (decimal):
Type:
Köppen climate type:
Mindat Locality ID:
210868
Long-form identifier:
mindat:1:2:210868:4
GUID (UUID V4):
a2fdbd5a-33e0-4b45-8b0b-c072f348337e
Other Languages:
Malagasy:
Fihadiam-batosoan' Antezambato, Kaominin' Antsakoamanondro, Distrikan' Ambanja, Faritr'i Diana, Madagasikara
Located 2,5 km W of the village of Antetezambato (which is located in the Maherivaratra Commune). The next-nearest city is Ambanja, around 20 km S of Antetezambato. The mining area covers ~20 hectares.The garnets are dug out of weathered intertidal rocks (in a mangrove swamp).
Groups of lustrous green colored andradite garnets (varieties demantoid and topazolite) crystals were found here in 2008-09 and presented at the Ste.-Marie-Aux-Mines mineral show in 2009. High-quality material is very rare. Unusual are pseudomorphs of fine-grained garnet + quartz after shells, corals and even ammonites, associated with demantoid crystals.
The demantoid is formed in sediments near the contact between intrusive and sedimentary rocks. The intrusive rocks are syenitic in composition and are considered either syenite (Razafindratsimba, 2017) or trachyte (Pezzotta, 2010,2011), whereas the sedimentary rock are considered either a lime-rich argillite( Razafindratsimba, 2017) or fine-grained sandstone interbedded with limestones (Pezzotta, 2010,2011). The mineralization is found in skarns formed along layer boundaries and fractures in the sediments, and along contacts with the intrusions. The skarn formation is caused by over-pressured pneumatolytic and hydrothermal fluids circulations generated by the intrusions. The result is a network of veins consisting of two different skarn types; a very fine-grained white/gray skarn where garnets are grossular (skarn 1) and a white/light green skarn (skarn 2) where the main garnet is andradite. The grossular typically has a thin rim of near end member andradite. The demantoid crystals are found is in fissures in skarn 2. Razafindratsimba, 2017) considers skarn 2 to be formed later than skarn 1.
Select Mineral List Type
Standard Detailed Gallery Strunz Chemical ElementsDetailed Mineral List:
| ⓘ Andradite Formula: Ca3Fe3+2(SiO4)3 Habit: Dominant dodecahedron combined with trapezohedron faces Colour: Yellow, via yellowish green, green, brownish green to brown. The crystals are sometimes color zoned. Description: Yellowish green to green crystals from here are marketed as demantoid. The individual crystals are found in vugs and fissures in skarns and can become up to 3 cm in size. |
| ⓘ Andradite var. Demantoid Formula: Ca3Fe3+2(SiO4)3 References: |
| ⓘ Andradite var. Topazolite Formula: Ca3Fe3+2(SiO4)3 References: |
| ⓘ Calcite Formula: CaCO3 |
| ⓘ Pyrite Formula: FeS2 |
| ⓘ Quartz Formula: SiO2 |
| ⓘ Stilbite-Ca Formula: NaCa4(Si27Al9)O72 · 28H2O |
| ⓘ 'Stilbite Subgroup' Formula: M6-7[Al8-9Si27-28O72] · nH2O References: |
| ⓘ Wollastonite ? Formula: Ca3(Si3O9) |
Gallery:
List of minerals arranged by Strunz 10th Edition classification
| Group 2 - Sulphides and Sulfosalts | |||
|---|---|---|---|
| ⓘ | Pyrite | 2.EB.05a | FeS2 |
| Group 4 - Oxides and Hydroxides | |||
| ⓘ | Quartz | 4.DA.05 | SiO2 |
| Group 5 - Nitrates and Carbonates | |||
| ⓘ | Calcite | 5.AB.05 | CaCO3 |
| Group 9 - Silicates | |||
| ⓘ | Andradite | 9.AD.25 | Ca3Fe3+2(SiO4)3 |
| ⓘ | var. Demantoid | 9.AD.25 | Ca3Fe3+2(SiO4)3 |
| ⓘ | var. Topazolite | 9.AD.25 | Ca3Fe3+2(SiO4)3 |
| ⓘ | Wollastonite ? | 9.DG.05 | Ca3(Si3O9) |
| ⓘ | Stilbite-Ca | 9.GE.10 | NaCa4(Si27Al9)O72 · 28H2O |
| Unclassified | |||
| ⓘ | 'Stilbite Subgroup' | - | M6-7[Al8-9Si27-28O72] · nH2O |
List of minerals for each chemical element
| H | Hydrogen | |
|---|---|---|
| H | ⓘ Stilbite Subgroup | M6-7[Al8-9Si27-28O72] · nH2O |
| H | ⓘ Stilbite-Ca | NaCa4(Si27Al9)O72 · 28H2O |
| C | Carbon | |
| C | ⓘ Calcite | CaCO3 |
| O | Oxygen | |
| O | ⓘ Andradite | Ca3Fe23+(SiO4)3 |
| O | ⓘ Calcite | CaCO3 |
| O | ⓘ Andradite var. Demantoid | Ca3Fe23+(SiO4)3 |
| O | ⓘ Quartz | SiO2 |
| O | ⓘ Stilbite Subgroup | M6-7[Al8-9Si27-28O72] · nH2O |
| O | ⓘ Wollastonite | Ca3(Si3O9) |
| O | ⓘ Stilbite-Ca | NaCa4(Si27Al9)O72 · 28H2O |
| O | ⓘ Andradite var. Topazolite | Ca3Fe23+(SiO4)3 |
| Na | Sodium | |
| Na | ⓘ Stilbite-Ca | NaCa4(Si27Al9)O72 · 28H2O |
| Al | Aluminium | |
| Al | ⓘ Stilbite Subgroup | M6-7[Al8-9Si27-28O72] · nH2O |
| Al | ⓘ Stilbite-Ca | NaCa4(Si27Al9)O72 · 28H2O |
| Si | Silicon | |
| Si | ⓘ Andradite | Ca3Fe23+(SiO4)3 |
| Si | ⓘ Andradite var. Demantoid | Ca3Fe23+(SiO4)3 |
| Si | ⓘ Quartz | SiO2 |
| Si | ⓘ Stilbite Subgroup | M6-7[Al8-9Si27-28O72] · nH2O |
| Si | ⓘ Wollastonite | Ca3(Si3O9) |
| Si | ⓘ Stilbite-Ca | NaCa4(Si27Al9)O72 · 28H2O |
| Si | ⓘ Andradite var. Topazolite | Ca3Fe23+(SiO4)3 |
| S | Sulfur | |
| S | ⓘ Pyrite | FeS2 |
| Ca | Calcium | |
| Ca | ⓘ Andradite | Ca3Fe23+(SiO4)3 |
| Ca | ⓘ Calcite | CaCO3 |
| Ca | ⓘ Andradite var. Demantoid | Ca3Fe23+(SiO4)3 |
| Ca | ⓘ Wollastonite | Ca3(Si3O9) |
| Ca | ⓘ Stilbite-Ca | NaCa4(Si27Al9)O72 · 28H2O |
| Ca | ⓘ Andradite var. Topazolite | Ca3Fe23+(SiO4)3 |
| Fe | Iron | |
| Fe | ⓘ Andradite | Ca3Fe23+(SiO4)3 |
| Fe | ⓘ Andradite var. Demantoid | Ca3Fe23+(SiO4)3 |
| Fe | ⓘ Pyrite | FeS2 |
| Fe | ⓘ Andradite var. Topazolite | Ca3Fe23+(SiO4)3 |
Other Regions, Features and Areas containing this locality
African Plate
- Diego Ambilobe basinBasin
Madagascar
- ⭔Antsiranana ProvinceProvince
Somali PlateTectonic Plate
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References
