Betroka District, Anosy, Madagascar (original) (raw)

ⓘ Albite

Formula: Na(AlSi3O8)

ⓘ 'Allanite Group'

Formula: (A12+REE3+)(M13+M23+M32+)O[Si2O7][SiO4](OH)

Localities:

Benato phlogopite mines, Benato Toby, Betroka District, Anosy, Madagascar
Ambatomena Toby, Bekorobo, Betroka District, Anosy, Madagascar
Antanimary phlogopite mine, Ambatomivary, Betroka District, Anosy, Madagascar

ⓘ 'Amphibole Supergroup'

Formula: A B2C5((Si,Al,Ti)8O22)(OH,F,Cl,O)2

ⓘ Analcime

Formula: Na(AlSi2O6) · H2O

ⓘ Anhydrite

Formula: CaSO4

ⓘ Anorthite

Formula: Ca(Al2Si2O8)

ⓘ Anorthite var. Labradorite

Formula: (Ca,Na)[Al(Al,Si)Si2O8]

ⓘ 'Apatite'

Formula: Ca5(PO4)3(Cl/F/OH)

Localities: Reported from at least 20 localities in this region.

Description: A 3 cm long, transparent, greenish crystal is reported by Lacroix (1913)

ⓘ Augite

Formula: (CaxMgyFez)(Mgy1Fez1)Si2O6

Description: Sample sold as kornerupine

ⓘ 'Bastnäsite'

Formula: (Ce/Nd/Y/REE)(CO3)F

ⓘ Beryl

Formula: Be3Al2(Si6O18)

Colour: Blue

ⓘ 'Biotite'

Formula: K(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2

Localities:

Itrongay (Itrongahy), Mahasoa Est, Betroka District, Anosy, Madagascar
Iankaroka corundum occurrence, Ianabinda, Betroka District, Anosy, Madagascar
Androngovato, Mahasoa Est, Betroka District, Anosy, Madagascar
Manivitsy, Mahasoa Est, Betroka District, Anosy, Madagascar
Ambatomena ruby deposit, Isoanala, Betroka District, Anosy, Madagascar

ⓘ Calcite

Formula: CaCO3

Localities: Reported from at least 11 localities in this region.

ⓘ Celestine

Formula: SrSO4

ⓘ 'Chabazite'

Habit: crystals < 8mm

ⓘ Chalcopyrite

Formula: CuFeS2

ⓘ Cheralite

Formula: CaTh(PO4)2

References:

Ferraris, Cristiano, Pignatelli, Isabella, Cámara, Fernando, Parodi, Giancarlo, Pont, Sylvain, Schreyer, Martin, Wei, Fengxia (2020) Laurentthomasite,Mg2K(Be2Al)Si12O30: a new milarite-group-type member from the Ihorombe region, Fianarantsoa Province, Madagascar. European Journal of Mineralogy, 32 (3) 355-365 doi:10.5194/ejm-32-355-2020

ⓘ 'Chevkinite Group'

Localities:

Betroka District, Anosy, Madagascar
Itrongay (Itrongahy), Mahasoa Est, Betroka District, Anosy, Madagascar
Isoanala, Betroka District, Anosy, Madagascar
Chevkinite occurrence, Ianakafy, Betroka District, Anosy, Madagascar
Androngovato, Mahasoa Est, Betroka District, Anosy, Madagascar

ⓘ 'Chlorite Group'

References:

Rakotondrazafy, Amos Fety Michel, Giuliani, Gaston, Ohnenstetter, Daniel, Fallick, Anthony E., Rakotosamizanany, Saholy, Andriamamonjy, Alfred, Ralantoarison, Théogène, Razanatseheno, Madison, Offant, Yohann, Garnier, Virginie, Maluski, Henri, Dunaigre, Christian, Schwarz, Dietmar, Ratrimo, Voahangy (2008) Gem corundum deposits of Madagascar: A review. Ore Geology Reviews, 34 (1) 134-154 doi:10.1016/j.oregeorev.2007.05.001

ⓘ Cordierite

Formula: (Mg,Fe)2Al3(AlSi5O18)

Localities: Reported from at least 6 localities in this region.

Habit: oval-shaped monomineralic aggregates

Colour: slightly bluish

Description: a very Mg-rich variety with ca. 7 mol. % of the iron component

ⓘ Corundum

Formula: Al2O3

Localities: Reported from at least 8 localities in this region.

ⓘ Corundum var. Ruby

Formula: Al2O3

References:

Giuliani, Gaston, Fallick, Anthony, Rakotondrazafy, Michel, Ohnenstetter, Daniel, Andriamamonjy, Alfred, Ralantoarison, Théogène, Rakotosamizanany, Saholy, Razanatseheno, Marie, Offant, Yohann, Garnier, Virginie, Dunaigre, Christian, Schwarz, Dietmar, Mercier, Alain, Ratrimo, Voahangy, Ralison, Bruno (2007) Oxygen isotope systematics of gem corundum deposits in Madagascar: relevance for their geological origin. Mineralium Deposita, 42 (3) 251-270 doi:10.1007/s00126-006-0105-3

ⓘ Corundum var. Sapphire

Formula: Al2O3

ⓘ Diopside

Formula: CaMgSi2O6

Localities: Reported from at least 11 localities in this region.

ⓘ Edenite

Formula: NaCa2Mg5(Si7Al)O22(OH)2

References:

Giuliani, Gaston, Fallick, Anthony, Rakotondrazafy, Michel, Ohnenstetter, Daniel, Andriamamonjy, Alfred, Ralantoarison, Théogène, Rakotosamizanany, Saholy, Razanatseheno, Marie, Offant, Yohann, Garnier, Virginie, Dunaigre, Christian, Schwarz, Dietmar, Mercier, Alain, Ratrimo, Voahangy, Ralison, Bruno (2007) Oxygen isotope systematics of gem corundum deposits in Madagascar: relevance for their geological origin. Mineralium Deposita, 42 (3) 251-270 doi:10.1007/s00126-006-0105-3

ⓘ Enstatite

Formula: Mg2Si2O6

Description: an enstatite with XMg values from 0.94 to 0.98, Al2O3 varies between 1.80 to 5.57 wt% and MnO is up to 0.14 wt% (Razakamanana et al. (2006)

ⓘ Enstatite var. Bronzite

Formula: (Mg,Fe2+)2[SiO3]2

ⓘ Epidote

Formula: (CaCa)(AlAlFe3+)O[Si2O7][SiO4](OH)

ⓘ 'Feldspar Group'

Colour: Pink to reddish

Description: Perthitic K-Feldspar. Sometimes Graphic Granite intergrowths with white/smoky Quartz

ⓘ 'Feldspar Group var. Perthite'

Colour: Pink to reddish

Description: Perthitic K-Feldspar. Sometimes Graphic Granite intergrowths with white/smoky Quartz

ⓘ Ferrohögbomite-2N2S

Formula: [(Fe2+,Mg,Zn,Al)3(Al,Ti,Fe3+)8O15(OH)]2

ⓘ Fluorite

Formula: CaF2

ⓘ 'Garnet Group'

Formula: X3Z2(SiO4)3

ⓘ Grandidierite

Formula: (Mg,Fe2+)(Al,Fe3+)3(SiO4)(BO3)O2

ⓘ Grossular

Formula: Ca3Al2(SiO4)3

ⓘ Gypsum

Formula: CaSO4 · 2H2O

ⓘ Hercynite

Formula: Fe2+Al2O4

ⓘ 'Heulandite Subgroup'

Formula: (Na/Ca/K)5-6[Al8-9 Si27-28 O72] · nH2O

ⓘ Ilmenite

Formula: Fe2+TiO3

ⓘ 'Indicolite'

Formula: A(D3)G6(T6O18)(BO3)3X3Z

ⓘ Kaolinite

Formula: Al2(Si2O5)(OH)4

References:

Popov, Daniil V., Spikings, Richard A., Scaillet, Stéphane, O'Sullivan, Gary, Chew, David, Badenszki, Eszter, Daly, J. Stephen, Razakamanana, Théodore, Davies, Joshua H.F.L. (2020) Diffusion and fluid interaction in Itrongay pegmatite (Madagascar): Evidence from in situ 40Ar/39Ar dating of gem-quality alkali feldspar and U Pb dating of protogenetic apatite inclusions. Chemical Geology, 556. 119841pp. doi:10.1016/j.chemgeo.2020.119841

ⓘ 'K Feldspar'

Localities:

Iankaroka corundum occurrence, Ianabinda, Betroka District, Anosy, Madagascar
Voronkafotra (Vorokafotra; Vohidava mine), Ianabinda, Betroka District, Anosy, Madagascar
Itrongay (Itrongahy), Mahasoa Est, Betroka District, Anosy, Madagascar
Sakoa, Nanarena Besakoa, Betroka District, Anosy, Madagascar

ⓘ Kornerupine

Formula: Mg3Al6(Si,Al,B)5O21(OH)

Localities:

Ianakafy (Inanakafy), Ianakafy, Betroka District, Anosy, Madagascar
Voronkafotra (Vorokafotra; Vohidava mine), Ianabinda, Betroka District, Anosy, Madagascar
Itrongay (Itrongahy), Mahasoa Est, Betroka District, Anosy, Madagascar
Betroka District, Anosy, Madagascar
Manivitsy, Mahasoa Est, Betroka District, Anosy, Madagascar

Habit: prismatic crystals up to 3-4cm long and 1cm thick. The prisms show the faces {100}, {010} and {110}. End faces are extremely rare and poorly developed. Only {111} could be identified.

ⓘ Laumontite

Formula: CaAl2Si4O12 · 4H2O

ⓘ Laurentthomasite (TL)

Formula: K◻2Mg2(Be2Al)[Si12O30]

Type Locality:

References:

Ferraris, Cristiano, Pignatelli, Isabella, Cámara, Fernando, Parodi, Giancarlo, Pont, Sylvain, Schreyer, Martin, Wei, Fengxia (2020) Laurentthomasite,Mg2K(Be2Al)Si12O30: a new milarite-group-type member from the Ihorombe region, Fianarantsoa Province, Madagascar. European Journal of Mineralogy, 32 (3) 355-365 doi:10.5194/ejm-32-355-2020

ⓘ 'Leptynite'

Localities: Reported from at least 7 localities in this region.

ⓘ Magnetite

Formula: Fe2+Fe3+2O4

Localities:

Ampasimainty, Bekorobo, Betroka District, Anosy, Madagascar
Iankaroka phlogopite deposit, Ianabinda, Betroka District, Anosy, Madagascar
Beravina, Ambaro, Tsaraitso, Betroka District, Anosy, Madagascar

ⓘ Marialite

Formula: Na4Al3Si9O24Cl

ⓘ 'Mica Group'

ⓘ Molybdenite

Formula: MoS2

Localities:

Benato phlogopite mines, Benato Toby, Betroka District, Anosy, Madagascar
Ambatomena Toby, Bekorobo, Betroka District, Anosy, Madagascar
Antanimary phlogopite mine, Ambatomivary, Betroka District, Anosy, Madagascar

ⓘ Opal

Formula: SiO2 · nH2O

Localities:

Benato phlogopite mines, Benato Toby, Betroka District, Anosy, Madagascar
Itrongay (Itrongahy), Mahasoa Est, Betroka District, Anosy, Madagascar
Beapompo II workings, Beampombo II, Betroka District, Anosy, Madagascar

ⓘ Opal var. Opal-CT

Formula: SiO2 · nH2O

References:

Popov, Daniil V., Spikings, Richard A., Scaillet, Stéphane, O'Sullivan, Gary, Chew, David, Badenszki, Eszter, Daly, J. Stephen, Razakamanana, Théodore, Davies, Joshua H.F.L. (2020) Diffusion and fluid interaction in Itrongay pegmatite (Madagascar): Evidence from in situ 40Ar/39Ar dating of gem-quality alkali feldspar and U Pb dating of protogenetic apatite inclusions. Chemical Geology, 556. 119841pp. doi:10.1016/j.chemgeo.2020.119841

ⓘ Orthoclase

Formula: K(AlSi3O8)

Localities:

Ankily, Ianabinda, Betroka District, Anosy, Madagascar
Beravina, Ambaro, Tsaraitso, Betroka District, Anosy, Madagascar
Betroka District, Anosy, Madagascar ? (more information)

Itrongay (Itrongahy), Mahasoa Est, Betroka District, Anosy, Madagascar

(more information)

Benono, Mahasoa Est, Betroka District, Anosy, Madagascar

(more information)

ⓘ 'Orthopyroxene Subgroup'

Localities:

Ianakafy (Inanakafy), Ianakafy, Betroka District, Anosy, Madagascar
Iankaroka corundum occurrence, Ianabinda, Betroka District, Anosy, Madagascar
Ambatomena ruby deposit, Isoanala, Betroka District, Anosy, Madagascar

Habit: euhedral to subhedral crystals characterized by the pyramidal faces {211}. Faces {101} not visible.

Colour: brownish

Description: The mineral represents a bronzite with (Fe, Mn): Mg = 15:85 and with Al largely substituting for Si.

ⓘ Pargasite ?

Formula: NaCa2(Mg4Al)(Si6Al2)O22(OH)2

ⓘ Phenakite

Formula: Be2SiO4

References:

Ferraris, Cristiano, Pignatelli, Isabella, Cámara, Fernando, Parodi, Giancarlo, Pont, Sylvain, Schreyer, Martin, Wei, Fengxia (2020) Laurentthomasite,Mg2K(Be2Al)Si12O30: a new milarite-group-type member from the Ihorombe region, Fianarantsoa Province, Madagascar. European Journal of Mineralogy, 32 (3) 355-365 doi:10.5194/ejm-32-355-2020

ⓘ Phlogopite

Formula: KMg3(AlSi3O10)(OH)2

Localities: Reported from at least 53 localities in this region.

ⓘ 'Plagioclase'

Formula: (Na,Ca)[(Si,Al)AlSi2]O8

Localities:

Ianakafy (Inanakafy), Ianakafy, Betroka District, Anosy, Madagascar
Ambatomena ruby deposit, Isoanala, Betroka District, Anosy, Madagascar
Vohidava corundum deposit, Betroka District, Anosy, Madagascar
Iankaroka corundum occurrence, Ianabinda, Betroka District, Anosy, Madagascar
Manivitsy, Mahasoa Est, Betroka District, Anosy, Madagascar

ⓘ Prehnite

Formula: Ca2Al2Si3O10(OH)2

Localities:

Benato phlogopite mines, Benato Toby, Betroka District, Anosy, Madagascar
Ambatomena Toby, Bekorobo, Betroka District, Anosy, Madagascar
Antanimary phlogopite mine, Ambatomivary, Betroka District, Anosy, Madagascar

ⓘ Pyrite

Formula: FeS2

Localities:

Benato phlogopite mines, Benato Toby, Betroka District, Anosy, Madagascar
Iankaroka corundum occurrence, Ianabinda, Betroka District, Anosy, Madagascar
Antanimary phlogopite mine, Ambatomivary, Betroka District, Anosy, Madagascar
Fangorolava phlogopite deposit, Jangany, Betroka District, Anosy, Madagascar

ⓘ Pyrophyllite

Formula: Al2Si4O10(OH)2

ⓘ 'Pyroxene Group'

Formula: ADSi2O6

ⓘ Pyrrhotite

Formula: Fe1-xS

Habit: Large masses; small grains & incomplete hexagonal crystals

ⓘ Quartz

Formula: SiO2

Localities: Reported from at least 6 localities in this region.

ⓘ Quartz var. Chalcedony

Formula: SiO2

ⓘ Quartz var. Smoky Quartz

Formula: SiO2

ⓘ Rutile

Formula: TiO2

ⓘ Sanidine

Formula: K(AlSi3O8)

Localities:

Itrongay (Itrongahy), Mahasoa Est, Betroka District, Anosy, Madagascar
Benono, Mahasoa Est, Betroka District, Anosy, Madagascar
Andangovato, Mahasoa Est, Betroka District, Anosy, Madagascar
Isoanala, Betroka District, Anosy, Madagascar

Habit: Prismatic

Colour: Yellow

Description: All the gemmy yellow "Orthoclase" is Sanidine

ⓘ Sapphirine

Formula: Mg4(Mg3Al9)O4[Si3Al9O36]

Localities: Reported from at least 10 localities in this region.

ⓘ 'Scapolite'

Localities: Reported from at least 8 localities in this region.

Colour: Pale yellow

ⓘ 'Scapolite var. Wernerite'

Localities:

Vohitramboa phlogopite deposit, Ambatomivary, Betroka District, Anosy, Madagascar
Antanimary phlogopite mine, Ambatomivary, Betroka District, Anosy, Madagascar
Fangorolava phlogopite deposit, Jangany, Betroka District, Anosy, Madagascar
Marovala phlogopite deposit, Isoanala, Betroka District, Anosy, Madagascar

ⓘ Sillimanite

Formula: Al2(SiO4)O

Localities:

Ampasimainty, Bekorobo, Betroka District, Anosy, Madagascar
Iankaroka corundum occurrence, Ianabinda, Betroka District, Anosy, Madagascar
Voronkafotra (Vorokafotra; Vohidava mine), Ianabinda, Betroka District, Anosy, Madagascar
Manivitsy, Mahasoa Est, Betroka District, Anosy, Madagascar

ⓘ Spessartine

Formula: Mn2+3Al2(SiO4)3

ⓘ Spinel

Formula: MgAl2O4

Localities: Reported from at least 21 localities in this region.

Colour: Blue-green

ⓘ Spinel var. Pleonaste

Formula: (Mg,Fe)Al2O4

ⓘ 'Stilbite Subgroup'

Formula: M6-7[Al8-9Si27-28O72] · nH2O

ⓘ Talc

Formula: Mg3Si4O10(OH)2

ⓘ Talc var. Steatite

Formula: Mg3(Si4O10)(OH)2

ⓘ Thorianite

Formula: ThO2

ⓘ Thorite

Formula: Th(SiO4)

ⓘ Thorite var. Orangite

Formula: Th(SiO4)

ⓘ Thortveitite

Formula: Sc2Si2O7

References:

Ferraris, Cristiano, Pignatelli, Isabella, Cámara, Fernando, Parodi, Giancarlo, Pont, Sylvain, Schreyer, Martin, Wei, Fengxia (2020) Laurentthomasite,Mg2K(Be2Al)Si12O30: a new milarite-group-type member from the Ihorombe region, Fianarantsoa Province, Madagascar. European Journal of Mineralogy, 32 (3) 355-365 doi:10.5194/ejm-32-355-2020

ⓘ Titanite

Formula: CaTi(SiO4)O

Localities: Reported from at least 6 localities in this region.

ⓘ 'Tourmaline'

Formula: A D3G6 (T6O18)(BO3)3X3Z

Localities:

Ianakafy (Inanakafy), Ianakafy, Betroka District, Anosy, Madagascar
Ampasimainty, Bekorobo, Betroka District, Anosy, Madagascar
Iankaroka corundum occurrence, Ianabinda, Betroka District, Anosy, Madagascar
Ambatomena Toby, Bekorobo, Betroka District, Anosy, Madagascar

Colour: black

ⓘ Zircon

Formula: Zr(SiO4)

Localities: Reported from at least 8 localities in this region.

Colour: Brownish to deep red

Description: Gemmy.