Manjaka, Sahatany Valley, Ibity, Antsirabe II District, Vakinankaratra, Madagascar (original) (raw)

Description: A. Lacroix (1912,1922) described columbite-(Mn)(Manganocolumbite) from Manjaka,using only visual means for analysis. Later von Knorring and Fadipe (1981)analyzes columbite-(Mn) from Manjaka and find that it is a tungstenian variety. Also as partially alteration of behierite (Pezzotta 2007)

ⓘ Danburite

Formula: CaB2Si2O8

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ⓘ Darrellhenryite

Formula: Na(Al2Li)Al6(Si6O18)(BO3)3(OH)3O

References:

Gadas, P., Novák, M., Vašinová Galiová, M., Pezzotta, F. (2023) Chemical composition of tourmalines from the Manjaka pegmatite and its exocontact, Sahatany Valley, Madagascar. Journal of Geosciences, 68 (3) 185-202 doi:10.3190/jgeosci.374

ⓘ Diopside

Formula: CaMgSi2O6

Description: Found in the exocontact zones of the pegmatite

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ⓘ Dolomite

Formula: CaMg(CO3)2

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ⓘ 'Dravite-Uvite Series'

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ⓘ Elbaite

Formula: Na(Li1.5Al1.5)Al6(Si6O18)(BO3)3(OH)3(OH)

Description: Described as a Mn-rich elbaite (elbaite manganésière) by Ranorosoa (1986)

ⓘ Fluorapatite

Formula: Ca5(PO4)3F

Habit: Small, mostly mm-sized hexagonal prismes

Colour: prusse blue

Description: Called "apatite manganiésifère" or "manganapatite" in litterature.

ⓘ Fluorapatite var. Manganese-bearing Fluorapatite

Formula: (Ca,Mn2+)5(PO4)3(F,Cl,OH) or Ca5([P,Mn5+]O4)3(F,Cl,OH)

Habit: Small, mostly mm-sized hexagonal prismes

Colour: prusse blue

Description: Called "apatite manganiésifère" or "manganapatite" in litterature.

ⓘ Fluor-dravite

Formula: NaMg3Al6(Si6O18)(BO3)3(OH)3F

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ⓘ Fluor-elbaite

Formula: Na(Li1.5Al1.5)Al6(Si6O18)(BO3)3(OH)3F

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ⓘ Fluor-uvite

Formula: CaMg3(Al5Mg)(Si6O18)(BO3)3(OH)3F

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ⓘ 'Ixiolite-(Mn2+)-Ixiolite-(Fe2+) Series'

Description: (Mn1,63Ta1,10W0,79Nb0,50)4,02 O8 (Ranorosoa 1986)

ⓘ 'Ixiolite-(Mn2+)-Ixiolite-(Fe2+) Series var. Wolframoixiolite'

Formula: (Nb,W,Ta,Fe,Mn)2O4

Description: (Mn1,63Ta1,10W0,79Nb0,50)4,02 O8 (Ranorosoa 1986)

ⓘ 'K Feldspar'

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ⓘ Lithiophilite

Formula: LiMn2+PO4

Description: Pink, translucent, prismatic crystals (rare) or masses in albite. Often with an aureole of manganese oxides.

ⓘ Londonite

Formula: (Cs,K,Rb)Al4Be4(B,Be)12O28

ⓘ 'Londonite-Rhodizite Series'

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ⓘ Magnesio-lucchesiite

Formula: CaMg3Al6(Si6O18)(BO3)3(OH)3O

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ⓘ Magnetite

Formula: Fe2+Fe3+2O4

ⓘ Manandonite

Formula: Li2Al4(Si2AlB)O10(OH)8

ⓘ Microcline

Formula: K(AlSi3O8)

ⓘ 'Microlite Group'

Formula: A2-mTa2X6-wZ-n

Description: As partially alteration of behierite

ⓘ Monazite-(Ce)

Formula: Ce(PO4)

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ⓘ Opal

Formula: SiO2 · nH2O

ⓘ Opal var. Opal-AN

Formula: SiO2 · nH2O

ⓘ Oxy-dravite

Formula: Na(Al2Mg)(Al5Mg)(Si6O18)(BO3)3(OH)3O

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ⓘ Phenakite

Formula: Be2SiO4

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ⓘ Phlogopite

Formula: KMg3(AlSi3O10)(OH)2

Description: A Di+Tr+Tur±Kfs±Qz±Cs-rich phlogopite in variable proportions are found in small bands in the exocontact of the pegmatite with the host rock.

References:

Novák, M.,Gadas, P.,Galiová Vašínová, M. & Pezzotta, F. (2013): Compositional variations in Cs,Li,Mg-rich beryl from exocontact of the complex Manjaka pegmatite, Sahatany Valley, Madagascar. GAG-MAC Winnipeg 2013, SY2-P3, p. 152-153

ⓘ Pollucite

Formula: (Cs,Na)2(Al2Si4O12) · 2H2O

Description: corroded

ⓘ 'Polylithionite-Trilithionite Series'

ⓘ 'Psilomelane'

Description: alteration of spessartine and perhaps also of columbite-(Mn) (Behier 1953)

ⓘ 'Pyrochlore Supergroup'

Formula: A2-mD2X6-wZ1-n

ⓘ '~~Pyrochlore Supergroup var. Betafite (of Hogarth 1977)'~~

Formula: (Ca,Na,U)2(Ti, Nb,Ta)2O6Z(OH)

Description: Behier (1953) describes small brown strongly refrigent crystals as "blomstrandite". Visual examination of the specimens collected by J. Behier and labelled blomstrandite, Manjaka in the Musée National de la Géologie in Ampandrianomby in Antananarivo, Madagascar is very similar to what later has been proved to be a hafnian zircon (per. com. Knut Edvard Larsen, 1999)

ⓘ Quartz

Formula: SiO2

✪ Rhodizite

Formula: (K,Cs)Al4Be4(B,Be)12O28

Habit: Up to 2 cm large well developed dodecahedral crystals modified by tetrahedron {111} faces

Colour: Pale to honey yellow; colorless. Transparent to translucent

Description: Occurs in saccharoidal albite close to the contact with the hosting marble, and in miarolitic cavities.

ⓘ Rhodochrosite

Formula: MnCO3

Description: Anhedral grains of pink lithiophilite may locally been replaced by rhodochrosite.

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ⓘ Rutile