(Fihadiam-baton' Antsongombato, FKT Antsentsindrano, Kaominina Andrembesoa, Departementa Betafo, Faritra Vakinankaratra, Faritany Antananarivo, Madagasikara)
Antsongombato gem mine refers to a small area where several LCT pegmatite dykes (of Danburite subtype) have been worked for gems, mostly red tourmaline and yellow londonite. Famous for its large (up to 7 cm) yellow crystals of rhodizite/londonite and for being the type locality of schiavinatoite. The locality is situated 4 km ESE of the small village Antsentsindrano which is situated 25 km southwest of Mahaiza (a relatively easy accessable marketplace) and south of the town Betafo in the central highland of Madagascar. The mine is located on the northern side of the Manentoakoho Mountain.
French colonists started mining here for red tourmaline in the beginning of the 20th century. And it was then abandoned in the 1930s. Later, in 1964-1965, a french colonist mined here, mostly for rhodizite specimens. In 1998 after thorough investigations in the area, the malagasy company, "Pyramide" started specimen mining here, especially for rhodizite-londonite specimens. Many good quality specimens was then recovered. The largest and best specimens of rhodizite/londonite came from one dike which measured 400 m long and 10-60 cm thick (Laurs et al 2002). In january 2001 the Pyramide company ceased their activities in the area. The area is still being worked in a much smaller scale for mineral specimens.
Refs.:
- Duparc,L.,Wunder,M., Sabot,R.(1910): Les minéraux des pegmatites des environs d´Antsirabe á Madagscar. Mémoires de la Société de Physique et d'Histoire Naturelle de Geneve, 36, 3, 283-407
- Lacroix, A. (1912): Sur quelques minéraux des pegmatites du Vakinankaratra (Madagascar). Soc. franc.min 35 , 76-78
- Laurs, B. M.; Pezzotta, F.; Simmons, W.; Falster, A.U & Muhlmeister, S. (2002): Rhodizite-londonite from the Antsongombato pegmatite, Central Madagascar. Gems & Mineralogy. 38 (4), 326-339
- Pezzotta, F.(1999): Madagaskar. Extra Lapis No. 17, 70-73
Demartin,F.et al (2001): Schiavinatoite,(Nb,Ta)BO4, The Nb Analogue of behierite. Eur. J. Mineral. 13, 159-165
- Simmons, W.B; Pezzotta,F; Falster, A.U & Webber, K.L.(2001): Londonite, a new mineral species: The Cs-dominant analogue of Rhodizite from the Antandrokomby granitic pegmatite, Madagascar. Can. Min., 39, 747-755
