Ilakaka Madagascar ( Sapphire Rush )

By Author: Alain Darbellay GGGems
Total Articles: 11
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ILAKAKA

· The plateau of Ilakaka in 1992.

Ilakaka is located on the road to Tulear,
south-west of Madagascar. The discovery of
sapphire in the current of 1998 transformed the area.

· Ilakaka in 1999.

It is in the accesses of the downwards brook named
Ilakaka that the first sapphires were found in 1998. The existence of gemmiferous minerals, including
corundum was known for a long time in the sandstones of
Isalo. French geologists having undertaken research in
1946 in particular. If their discovery did not cause particular
interest at the time, several reasons can be advanced :
the political instability which reigned after the second
world war in the colony, and the fact that the majority
of corundums coming from the area of Ilakaka must be

heated to be marketed, indeed, a blue stone, but cloudy,
could not inevitably let suppose to its discoverers that it
would become pure and transparent after a suitable heat
treatment. ...
... Moreover, knowledge in this field remained
summary at that time. In Ilakaka, the arrival of merchants
coming from Thailand and from Sri-Lanka changed things,
because this group of purchasers became experts in "the
" Tsy misy mandronono, tsy misy prix" enhancement of corundum." Thus, the cloudy stones of
This sentence is none by everyone in better quality will be often sold as (untreated Sri-Lankan
Ilakaka. sapphires) on the international market, this because of
It means that : " if the stone is not milky, the difficulties in detecting heating treatment in a stone
its owner will not get price for it." from Ilakaka not containing other inclusion only one
haze of fine titanium drops, reabsorbed after heating.
( Note: that true untreated Sri-Lankan sapphires are rare.)


The excavations follow the gravel deposits which the Impressing holes bore the sandstones of
Madagascans call lalam' bato, (the way of stones.) Ilakaka testifying to the fever of sapphire.

Ankaboka, one of the many gemmiferous places of the area.

· Maromiandry is located
The sivany (sifting of gravels) in Maromiandry. 40 kilometers north of the
Seldom practiced dry as in this place distant trunk road between
from a river. Ilakaka and Sakaraha.

The sifting of gemmiferous gravels in river close to Maromiandry.


· VOHIMENA VAOVAO, 25 kilometers far from
Ilakaka. One of quote headlight of the sapphires
production.

The higher edges of the rivers abound in sapphires,
chrysoberyls, etc. Here in the area of Vohimena vaovao.

The sandstones, fragile, have been knife cut by the river.

SANDSTONES of ISALO
The base of the group of Isalo is entirely continental.
Sometimes significant marine incursions and of long
duration were introduced into the medium and higher
parts. The group of Isalo begins at the top from lower
Triassic and continues until the end of the Jurassic
means.
One separates there:
Isalo I, at the base, especially sandy, continental.
Isalo II, argilo - sandy with some marine intercalations.
Isalo III, argilo - sandy with side passage to great marine
formations. The essential characteristic of the Isalo formations is their
main constitution of soft sandstones, very permeable,
badly cemented which disaggregate easily on surfaces
by giving thick siliceous sand coverings.
The porous nature of the sandstones constitutes an
excellent tank which stores the water of the rains to
restore it during the dry season.

· Sakalama, 60 kilometers south from Ilakaka. MADAGASCAN CORUNDUMS
At the back, ruiniform sandstones of the Isalo range.

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