Andranondambo Sapphire discovery ( Madagascar )Written by Alain Darbellay GGGems
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formations have only a very weak development. It is necessary to quote alluvial plains of Androtsy, Esira, Sangoria and Pisopiso. A notable calcareous carapace covers most of area. Metamorphized dolomitic limestone. Near Andranondambo The anosyans granites are regarded as synorogenes, eocambrians formed in androyans series to which an age higher than 2400 MY is allotted. The esirians granites present very variable crushings of intensity which often give them a gneissic facies . There is sometimes passage to orthogneisses. General foliation is sub meridian. The occurrences of Andranondambo area were industrially exploited since 1993 and have been almost abandoned few years later. Actually, it is very difficult to exploit sapphire direct in mother rock, because corundum is not concentrated enough. Furthermore, hardness of rock makes its exploitation very expensive. ¦ MADAGASCAR GEM SAFARI ¦ ABOUT ILAKAKA ¦ MADAGASCAN CORUNDUMS ¦
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Pakistan gem safariWritten by Alain Darbellay GGGems
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deposit of natural cherry topaz in world. -------------------------------------------------- · Emerald from Mingora, main city of Swat. The deposit discovered in 1958 was closured and monopolized by government, it is what compelled certain inhabitants residing in neighborhood to dig under their house in order to research prohibited treasure. TECTONIC CONTROL OVER EMERALD MINERALIZATION IN SWAT. It is in Swat valley that Alexander of Macedon fought Emerald and chromian tourmaline occur in carbonate-talc/ and won some of his major battles before crossing over serpentine/chlorite rocks, carbonate-bearing talc schists, to plain of Pakistan. and associated quartz veins near Mingora, Charbagh, and Let us note that emerald was known for a long time Shangla. The rocks are altered ultramafics found in a in this valley, thanks to an analysis on a stone of a discontinuous belt of volcanic, volcano-sedimentary, and Gallo-Roman ear-ring, witch shown that this emerald sedimentary rocks that have undergone high P-low T originated in of mines located in Swat valley. metamorphism. This thanks to measurement of report/ratio of
This is at occasion of one of our visits in valley, that some children tolled us that they found some fragments of emerald in Swat river. concentration of isotopes 18O and 16O. Indeed, isotopic composition out of oxygen of this precious stone is dependent on that of rock where it crystallized. · Central street of Mingora. ------------------------------------------------- Blue-green tourmaline from Kunar valley, Afghanistan. Nimak mendy, old Peshawar, on road to Afghanistan. Mountains of Afghanistan. Alain talking with our Afghan friend Sarbaz. GGGEMS.COM
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