|DISCOVERING OPAL DEPOSITS OF SHEWA IN ETHIOPIA|
In the sky a diffused light outlines some distant hills and caresses tufts of grass undulating in bracing air. Eastward in the distance, subtle drops in the horizon curve and slight changes in the cloud pattern indicate “finis terrae”. One can make out precipices where the plateau subsides into dizzy cliffs sloping down in terraces to the valley of the Ethiopian rift. We are at a height of 2,800 metres and moving through volcanic rocks : light –coloured tufa, andesits and basalts. Our driver, Asnaka, is 20 years old. He always knows the best trajectory and most appropriate engine speed to choose and we are cruising at the pace of a liner. We left Addis-Ababa three hours ago, went through the village of Sendafa and the towns of Chacha and Debré Birhan. We crossed the watershed between the Awash and the Blue Nile. To join the northern road, the historic road linking Addis-Ababa and Asmara in Eritrea, we left the capital city along the butchers’ street : alongside blocks covered with quartered carcasses, plentiful supply of meat. We met shepherds leading their goats to the big town, processions of donkeys loaded with bulging bundles or drawing carts in the middle of heavy traffic. Eventually we left behind huge eucalyptus trees so well-acclimatized to African soil. The previous day we had taken leave of my friend Eyassu Bekele, who works in bole Road offices and manages Eyaopal. We were equipped with topographical maps and a proper licence allowing us to go all over the mining concession. Sitting at the rear of our 4x4 car Adisu makes comments, explains, he is the one who knows. Adisu has an academic background, he studied biology with a liking for ornithology. He is the opal expert within the Eyaopal company. Over the 10 previous days spent in the capital city and in Debré Zeit we had passionate discussions about the rifts, volcanism, Lucy, endemic fauna and flora, opal varieties and their locations. The landscape changes, we are approaching the Tarma Ber tunnel (1).
1 - Mezezo, a farming village located at an altitude of 3,000m, is a zone were opal mining concessions are numerous
We are proceeding at an altitude of more than 3,000 metres between impressing gorges. The plateau gently sloping in terraces, is scattered with bright-green patches. Tef is grown here: this cereal is peculiar to Ethiopia, it resists the important climatic variations the high-land inhabitants have to put up with. Some farms nestle here and there, often in groves in the middle of fields where volcanic bombs can sometimes be found. Altitude and latitude combined generate a subalpine temperate climate (2). The Shewa plateau and Northern Abyssinia are the African “water tower”. Powerful rivers have their source there e.g. the mythical Blue Nile. The high lands stop the summer monsoon coming from the Indian Ocean. Rainfall is important. In March, the rainy season is moderate. But from the end of June to the end of September, rainfall is so heavy that it is very difficult, even impossible, to travel on roads and trails. Associating silica-rich acid lava and plentiful water is favourable for opal formation. Before the Tarma Ber pass, we leave the asphalt road for paths leading to the Eyaopal concession, we head northwards along the plateau rim. The sun does not shine, the sky is white and the air fresh. We arrive in Mezezo, a mountain village (p.1).
As we stop in front of the largest house, lots of children swarm around our vehicle : our first lively contact. It is market day and farmers come from afar. I cannot forget that civil wars and famine have badly hit this area. This bustling life impresses me so much ! Adisu urges me to interrupt my awkward discussions with the children and meet him inside the inn. Two brothers run the place and they are both village chiefs and teachers. Adisu negotiates with them the practical details concerning our stay and our protection. Before leaving Mezezo we eat injeras (3). We are going to walk as far as the sites where Eyaopal mine opals in a concession of about 100 km2. After a few hundred metres, the horizontal path opens onto slopes and at the same time we get out of the cloud lining the plateau side (p.2). Suddenly a magical landscape meets our eyes.
We are standing above a series of terraces going down towards a valley marked out with deeply dug gorges and then we lose sight of the slopes which, in the distance, end up to the rift valley. The landscape covered with fluorescent green tef fields,offers a hypnotic distance standard. At the top of some hills, buildings come out among big trees. Adisu explains to me that they are churches. He draws my attention to the left and to the right below, to the light-coloured outcrops : there are opal-rich rocks. We start going down along a path bordered with beautiful flowers. It looks as if they had coordinated their colours with the birdsongs. Shall I be lucky enough to see a superb sterling ? After a one-hour walk we arrive at one of the sites located 300 metres under the plateau edge.
3 - Rock with opal nodules, particularly visible on the collapsed block, height of the level : 4m
A rocky mass, on which nothing grows, outcrops with a length of 50m and a height ranging from 1 to 4 m, it is full of nodules whose average diametre is 3.5cm. A 300 m3 protruding part shows numerous nodules, such as hemispherical holes left by removed nodules but also cavities either empty or containing a little opal (p.3). This quarry seems to me an occasional one. Actually, in some spots, the rock side is vertical and compact, some blocks reaching up to one metre in length strew the ground and present perfect structure sections. The nodules are closely linked to the rock and cannot be extracted without breaking. Common opal filling them looks like flint. It is often stratified. In a rocky mass, nodules sometimes have the same aspect, opal has formed in the same way (strata are alike). It can be compared to the fact that colourful opal is found together with a significant volume of nodules. In some cases, the external crust of a nodule shows iridescence, the presence of opal inside is almost certain. I remember a story : in Queensland, Australia, Joe Knehr had discovered in Hayricks a patch of boulders (4) measuring several square metres and containing opal, and the substance between the boulders as well. In this area, where rock has been badly eroded, I can easily tear off nodules of 0.5 to 10 cm in diametre.
4 - High density of rhyolitic nodules, the one in the middle on the right measures 3cm in diametre.
Some of them are broken and point opal. It varies a lot : white, yellow, orangy, ocre, grey, black, chalky or shiny, translucent and rarely transparent, I cannot notice any play of colours. In some groups of nodules, well-marked and various coloured strata suggest that the “filling” has been a discontinuous process in changing conditions. A few metres farther, the density of nodules surprises me : 5,000 to 8,000 per cubic metre. They adjoin oneanother as if they had been seperated from the hosting rock (unless the latter had been moved away) and then compacted (p.4). The formation patterns of Ethiopian opal should become more refined. I am sceptical and remember the biggest nodule Eyassu ever found : it was more than 15 cm in diametre !
5 - Precious opal nodule of more than 15cm in diametre, definitely a museum piece (EYAOPAL collection).
We are standing on a rock shelf at the base of a huge cliff ledge, the terrace is cultivated and a farm stands 100 metres away. A few cheerful children, hidden behind a row of shrubs, spy on our small group. The owner of the place keeps a close watch on Eyaopal’s behalf, the concessionaire (5). After taking measurements and photographs, we head for another outcrop 200m away, a place where my friends found fire and white opal with a play of colours. With the farmers helping them, they dig into the crumbly rock to remove opal nodules. After working for a while, the excavation is filled up again with earth in order to avoid “looting”. I observe, measure, take pictures : close-ups with my numerical camera and overall views with the Minox. The nodules are very numerous here. Some show nice opalescence with bluish shades. Once again I am struck by the opal sides showing the same strata whatever the nodule. Many of them are partly full of opal and sometimes empty. In this case the surface is very special : it is rippled, reticulated with thin bubbles, similar to the surface of gelled oily liquid floating on denser water. Both the direction of strata and opalized silica gel surfaces allow to come to relevant conclusions, provided we admit that they formed horizontally (surface of a liquid in the gravitational field of the earth). It enables me to measure the present angle of layers compared with the horizontal line at the time opal was formed. The largest angle I note down is at 30°. I can also observe small faults, fractures and cracks (p.6).
6 - Nodule partly full of stratified opals
No piece of equipment has access to this place and only the surface of the deposit was mined. But 10 or 20 metres below the eroded surface, rock quality must be much better. Two other companies, Rugen and Abbai (6), are mining in the north about 5 or 15 kms away. With a large team Abbai have dug about 8m deep : they brought out sound compact rocks containing bound nodules full of beautiful orangy transparent fire opal. The opal-rich deposits are scattered over hundreds of km2. In the south Eyaopal extract from another outcrop brown opal whose nodules are small but of excellent quality and beautifully fire-coloured. Adisu announces that we have to go back to Mezezo. I look up at the top of the overhanging cliffs. In the middle of the rainy season, water must pour down with extreme strength, as evidenced by the impressive gullies. It could unearth opal much more efficiently than pickaxes can do. We had met very few people when going down, going up is completely different. The inhabitants of numerous farms scattered around the village are coming back from the market. We pass whole families. Riding donkeys or walking, mountain people go back to the fertile high valleys. They often take the opportunity to stop and have a friendly chat. Adisu translates. I am fascinated by these people, their attitude testifies to such patience and pride ! A little higher, where the steep path narrows, I swerve around her to let her go past… while talking to me she takes my hands, I do not understand her amharic words but I understand their meaning : she is touched by my gesture. I have no idea about her age, her face is extremely beautiful, almost unreal. I will never forget the Lady of the cliffs.
Opal deposits of Shewa are huge, others exist in Ethiopia. What is their real potential ? Will the inhabitants of Mezezo see one day their harsh living contitions improve thanks to opal business ? One thing is certain : several year will be required until their life quality standards are met and they take their obvious place on the market. I saw the superb sterling bird in Lalibela (7) , it was jet-black, flew off the shade of a tree and sparkled with bright blue colours in the sun rays. My Ethiopian friends name superb sterling the rare black opals adorned with deep blue and purple colours (8) ( p.7).