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Tourmaline from
Antandrokomby pegmatite, Manandona Valley, Sahatany Pegmatite Field (Mt Bity (Ibity) area), Vakinankaratra Region (Betafo - Antsirabé region), Antananarivo Province, Madagascar

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Antandrokomby pegmatite, Manandona Valley, Sahatany Pegmatite Field (Mt Bity (Ibity) area), Vakinankaratra Region (Betafo - Antsirabé region), Antananarivo Province, Madagascar
© O. Dziallas
Description
Comments:Nizamoff et al (2000) describes 3 types of tourmalines found at Antandrokomby : Type I: prismatic zonated crystals up to 30 cm with dark-olive-brown core and thin dark-red rim. These were found mostly in the massive pegmatite (and which rarely protruded into the pockets).
Type II: stubby, zoned, reddish-purple up to 4 cm with dark-olive brown cores and dark red rims (found in miarolitic pockets)
Type III: Vibrant pink unzoned crystals less than 2 mm which forms masses of fibrous crystals.

Nizamoff et al. (2000) further states that the types I and II from Antandrokomby have dark brown cores that are schorlitic in composition.
Weber et al (2002) further states: " Electron microprobe analyses reveal that the tourmalines are not liddicoatite, but principally schorl to elbaite in composition".

Ranorosoa (1986) analyzes pink, green and brownish tourmaline found at the pegmatite contactzone (equal to Nizamoff et al.'s type I) and find it to be elbaite in composition (Look under elbaite for further info)




Colour:red, pale rose, green; reddish-purple; dark-olive brown
Quality of samples:not specified / average specimens
Confirmation
Validity:Believed Valid
References
References:Palache, C., Berman, H., & Frondel, C. (1951), The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana, Yale University 1837-1892, Volume II: 330.; - Nizamoff, J.W.; Falster, A.U.; Pezzota, F. ; Simmons, W.B.; Hanson, S.L. and Webber, K.L. (2000): Recent mining at the Antandrokomby pegmatite, Madagascar. 26th Rochester Mineralogical Symposium. Rocks & Minerals, july 2000
Associated minerals:
Associates:Rhodizite
Data
Mineral Data:Click here to view Tourmaline data
Locality Data:Click here to view Antandrokomby pegmatite, Manandona Valley, Sahatany Pegmatite Field (Mt Bity (Ibity) area), Vakinankaratra Region (Betafo - Antsirabé region), Antananarivo Province, Madagascar
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Mineral and/or Locality
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