Andranondambo Sapphire discovery ( Madagascar )

© 2004 ... All rights ... ... in 1991 >> ... division we can ... 1 the volcanic strong mass of Androy, it's far included with thorny bush and meadows. 2 the gneiss
© 2004 All rights reserved.
Tranomaro in 1991 >>
Geographical division
we are able to distinguish:
1 the volcanic solid mass of
Androy, it's far protected with
thorny bush and meadows.
2 the gneissic area of to
Mandrarean Androy, fields
plains and hills, rare zones
of savanna on of purple floor on the time
calcareous carapace. of the outstanding
Altitude varies there from dryness in
six hundred meters at the hills the south.
to 250 meters at the lowest.
3 the western slope of the excessive Anosyans
chains which tops are staged among
1500 and 2000 meters. it's far a area of
Geological divisions.
1 Crystalline schists.
Gneiss with diopside, syenitic eysies
gneisses, arteritic injections, gneiss at
cordierite, and many others.
2 antique eruptive rocks.
Pegmatites, Dissogénites, Esirians
granites , charnockites, kalambatreans
granites, overdue granites .
three recent eruptive rocks.
(Volcanic strong mass of Androy)
a) A the base, a thick basaltic
subhorizontale series .
b) Basaltic dykes. On the street to Andranondambo
c) A thick better subhorizontale rhyolitic collection.
d) Rhyolitic dykes .
4 current formations.
If russet-crimson sands are excluded, the recent
formations have best a very susceptible improvement.
it's far important to quote the alluvial plains of
Androtsy, Esira, Sangoria and Pisopiso.
A super calcareous carapace covers most of the area.
Metamorphized dolomitic limestone.
near Andranondambo
The anosyans granites are appeared as synorogenes, eocambrians
formed within the androyans series to which an age better than 2400 MY
is allocated.
The esirians granites present very variable crushings of depth which
frequently deliver them a gneissic facies .
there's every so often passage to orthogneisses. preferred foliation is sub meridian.
The occurrences of the Andranondambo location have been industrially exploited seeing that 1993 and have been
almost deserted few years later. really, it's far very difficult to make the most sapphire direct in
mother rock, because corundum is not concentrated enough. furthermore, the hardness of the
rock makes its exploitation very steeply-priced.
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