Madagascar gem safariWritten by Alain Darbellay GGGems
© 2004 gggems.com All rights reserved. MADAGASCAR GEM SAFARI 2 Sapphire from Maromby in a metamorphic limestone. ( Andranondambo area.) Looking for sapphire on ground in 1992. Sapphires from Andranondambo, discovered in 1991. ( South-East of Madagascar ) In 1658, Flacourt, governor of Fort-Dauphin mentions sapphires in south of Madagascar. In 1808, Barthélemy Hugon writes that in valley of Ambolo there is a so beautiful stone and so rare that lapidaries have not been able to recognize it and it was above of all that is not diamond. ... In 1991, at time of great dryness in south, sapphire samples are found, several centuries after their first discovery. The son of Mrs. Dauphine, innkeeper in Tranomaro, main village of valley, was among prospectors. Actually, one of most beautiful quality in world is just leaving ground. The area of Tranomaro is characterized by an extreme calcic and magnesian paragneiss abundance: gneiss with diopside, plagioclasites, pyroxenites, wernerites, wolastonite limestones, with varied leptynites, generally with garnet, kinzigites, quarzites. One finds there rather frequently syenitic gneisses or lamboanites. Gneisses of injection are very frequent. The typomorphic minerals are: basic diopside, scapolite, calcite, plagioclases, wollastonite, garnet, cordierite and corundum. East of Tranomaro, arteritic and eyesys injections assign gneisses at leptynites. Cordierite gneiss bands are deeply injected bed by bed, injection has introduced magnetite in abundance. Wollastonites form ptymatic lenses with Marohotro, 18 km. south from Andanondambo. folds very tortured at middle of limestone. Note: The sapphire on left comes from Ambandanira, and aluminous anorthites or sakenites. that on right-hand side from Maromby (area of Andranondambo) Sapphire from Behataza plateau (Andranondambo area) Sapphires from Ilakaka. One of various holes in sandstone forming ( South-West of Madagascar ) deposit of Ilakaka discovered in to 1998. Blue sapphires , pink and violet, Ilakaka area. SANDSTONES OF ISALO. The white sandstones of Isalo present imposing stratifications intersected with gravel beds and small conglomerates. These soft sandstones resisted to erosion and taken a ruiniform relief because presence of braces siliceous veins. The mineral-bearing deposits include : a deposit of generally classified gravels, richest part and larger elements being at base of bed - rock. MORE ABOUT ILAKAKA
Andranondambo Sapphire discovery ( Madagascar )Written by Alain Darbellay GGGems
© 2004 gggems.com All rights reserved.
Tranomaro in 1991 >> Geographical division We will distinguish: 1 volcanic solid mass of Androy, it is covered with thorny bush and meadows. 2 gneissic zone of to Mandrarean Androy, fields plains and hills, rare zones of savanna on of red ground At time calcareous carapace. of great Altitude varies there from dryness in 600 meters on hills south. to 250 meters at bottom. 3 western slope of high Anosyans chains which tops are staged between 1500 and 2000 meters. It is a field of meadows. Geological divisions. 1 Crystalline schists. Gneiss with diopside, syenitic eysies gneisses, arteritic injections, gneiss at cordierite, etc. 2 Old eruptive rocks. Pegmatites, Dissogénites, Esirians granites , charnockites, kalambatreans granites, late granites . 3 Recent eruptive rocks. (Volcanic solid mass of Androy) a) A base, a thick basaltic subhorizontale series . b) Basaltic dykes. On road to Andranondambo c) A thick higher subhorizontale rhyolitic series. d) Rhyolitic dykes . 4 Recent formations. If russet-red sands are excluded, recent