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GEMSTONE ORIGINS<br />
MANY OF THE MINERS WERE FAMILIES WORKING<br />
IN SMALL GROUPS WITH WOMEN DOING MUCH<br />
OF THE HEAVY LABOUR<br />
PICKS, SHOVELS, BUCKETS AND HUMAN MUSCLE<br />
WERE THE ONLY MINING TECHNIQUES USED IN<br />
THE SAPPHIRE FIELDS<br />
in the country are to do with religious sites<br />
such as the Rock-Hewn Churches at Lalibela,<br />
which is a UNESCO World Heritage site. This<br />
site consists of 11 medieval monolithic cave<br />
churches from the 12th to 13th centuries<br />
and are still a place of pilgrimage and<br />
worship today.<br />
SAPPHIRE FIELDS NEAR CHILA<br />
Our expedition started with the sapphire<br />
fields near Chila. This was an area where<br />
we had the least information as to what<br />
was going on and did not know what<br />
to expect as far as the size of the mining<br />
area, the amount of miners involved or the<br />
nature of the mining. While much of what<br />
we witnessed met our preconceived ideas<br />
of the artisanal mining operations, seeing<br />
the exact nature of the mining proved<br />
very interesting, as well as learning about<br />
the reported transformation of the socioeconomic<br />
nature of the area.<br />
GEOLOGY<br />
Based on analytical results, it is clear that<br />
the sapphires are related to alkali-basalt<br />
flows. According to geological maps, there<br />
are several alkali basalt outcrops in the area,<br />
but the maps don’t indicate their presence<br />
around Chila. However, there are clearly<br />
basalt flows near the sapphire mines. Basalt<br />
flows can cover incredibly large areas<br />
with thick layers of molten rock, often in<br />
successive events.<br />
Based on our observations, the sapphirecontaining<br />
basalt flows were deposited<br />
on a flattened basement. This basement<br />
contains heterogeneous rocks of a granitic<br />
composition that belong to the Precambrian<br />
era (older than 540 Ma). The basalt flows<br />
are much younger and were deposited<br />
in the Cenozoic period (younger than 65<br />
Ma). The basalts erode much easier than<br />
the basement, creating a very wide valley<br />
flanked by flat plateaus.<br />
In the centre of the valley, we could see<br />
exposed basement. The sapphires have<br />
been released from their basalt host<br />
rock by weathering. The richest sapphire<br />
concentrations are found in the centre of<br />
the valley near the riverbed, although many<br />
miners are also working on the hill flanks.<br />
According to the locals, sapphires have also<br />
been found on top of the basalt plateaus,<br />
indicating that a lot of the basalts are<br />
sapphire bearing.<br />
MINING<br />
All of the mining we saw was classic<br />
artisanal mining on the secondary deposits.<br />
The deposits are ideal for artisanal mining<br />
techniques and family/community mining<br />
efforts. We saw no mechanisation in the<br />
mining whatsoever. All the miners in the<br />
area first dug pits with picks and shovels.<br />
Then, the gravel was taken out of the pits,<br />
often by just flinging it to the top of the pit<br />
with a shovel or by using buckets. It was<br />
then sorted through for sapphires by hand,<br />
often with just dry picking.<br />
It appeared that the dry sorting missed<br />
many of the smaller size sapphires and that<br />
most of the stones the artisanal miners were<br />
recovering were above one gram. This was<br />
also evident when we tried to buy samples<br />
for research in one-carat to half-gram sizes.<br />
It was difficult to find any sapphires in that
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