On March 3 the archaeology sleuths went back to the Christoffel park. The search for mining activities on the sides of the Seru Francisco Jobo is far from over. Last week we canvassed a part of the side of this mountain to the North of the known manganese mines. We found some areas where some mining activity could be seen. We assumed that these were trial pits.
This time we went searching for more activity to the South of the known mines on the Eastern and the Western slope of the mountain.
We parked our cars at the same spot as last time and went from there uphill a bit more to the South of our track from last time. Some of the sleuths had found there some traces of mining close to the top. So that was our first target.
And indeed there was a rather large area where mining activities were done. This time we concluded that this was not a trial pit but that this was an area where surface mining was done. Continuing our search close under the ridge of the mountain we found a second area where obviously mining activities had taken place; so also here a surface mine. This brought Fred to the idea that maybe surface mining was the normal practice for manganese mining as it is in the rest of the world and that the two tunnels were trials to find out if there was more manganese inside the mountain. That would explain why the accessible tunnel suddenly stops. What we see is that there is far more manganese on the surface than inside the mountain. At least that is the current situation. We see far more traces of manganese at the surface than we have found in the walls of the tunnel.
The plant to process the manganese is at the Western (Jerimi) side of the Seru Francisco Jobo so it is probable that originally manganese was found on that side of the mountain. So after a break we crossed the ridge and continued our search on the Western slope. Unfortunately we didn't find any manganese on this side of the mountain. It could be hidden under the fields of Bromeliads but even then we should have found some debris of mining activities. The area that we covered has a different type of rocks than at the other side of the ridge.
The Seru Francisco Jobo is an elongated mountain so we have some more area to cover before we can conlude that there was no mining at the Jerimi side of the mountain.
After a while we decided to quit. We once again crossed the ridge and started the difficult descend towards our cars. The slope is rather steep and there is a dense vegetation.
Next week we will come back to cover more area on both sides of the Seru Francisco Jobo more to the South-East of the farthest point that we reached this time.
I had taken some rocks with me from the surface mines to try to do some processing at home. After searching the Internet I found a method that looks the best doable except for the last step that involves a temperature that I cannot produce at home.
A short description of the processing follows:
For applications in which pure manganese is preferred, manganese ores are roasted to obtain an MnO calcine, and this is dissolved in sulfuric acid to form a manganous sulfate solution. The addition of ammonia precipitates iron and aluminum, and the addition of hydrogen sulfide precipitates arsenic, copper, zinc, lead, cobalt, and molybdenum. The purified solution is then fed into the cathode portion of an electrolytic cell, and, with the passage of electric current, manganese is deposited in layers a few millimetres thick on a stainless-steel cathode sheet. Cathodes are extracted periodically, and the manganese deposits are removed by hammering. The flakes are heated to 500 °C (925 °F) to remove hydrogen, resulting in a powdered manganese of greater than 99.9 percent purity.
Other processes involve smelting of the ores and then further processing; this is certainly not doable at home. But studying these processing methods brings me to the question what was done at the processing plant at Jerimi. Certainly no electrolytical process because that would have required a lot of electric energy which was certainly not available at that time (around 1880) at that location. Most probably only some refining of the raw ore was done to create a better exportable product. A renewed visit to the processing plant can maybe clarify that. As far as I remember there was a furnace (at least there is a chimney) and there are some tanks that can hold fluids. So that means yet another visit to this area but then at the Jerimi side.
- Our track (blue) projected on the Werbata map Our track (blue) projected on the Werbata map
- Large Palu di sia Large Palu di sia
- Manganese inside this rock Manganese inside this rock
- Lichen and usnea on a rock Lichen and usnea on a rock
- Manganese on this rock with tool marks Manganese on this rock with tool marks
- More manganese More manganese
- Surface mine Surface mine
- Surface mine Surface mine
- Manganese Manganese
- Nice small tree full with usnea Nice small tree full with usnea
- View from the top of the Seru Francisco Jobo View from the top of the Seru Francisco Jobo
- Lichen on a tree Lichen on a tree
- Our next target - a suspicious rock formation Our next target - a suspicious rock formation
- Manganese just beneath the crust of this rock Manganese just beneath the crust of this rock
- This rock contains calcite This rock contains calcite
- Not a tunnel but a small excavated opening Not a tunnel but a small excavated opening
- Another excavated opening in the rocks Another excavated opening in the rocks
- Inside the opening remaining traces of manganese Inside the opening remaining traces of manganese
- Tree covered with orange-yellow lichen Tree covered with orange-yellow lichen
- Close-up of the tree Close-up of the tree
- Guard overlooking the surface mines Guard overlooking the surface mines
- Time for our apple break Time for our apple break
- Wood sculpture Wood sculpture
- Also here traces of a surface mine Also here traces of a surface mine
- Fred during his apple break Fred during his apple break
- Panoramic view in the direction of St Cruz Panoramic view in the direction of St Cruz
- The lagune of St. Cruz The lagune of St. Cruz
- Fred points to more traces of manganese Fred points to more traces of manganese
- Field of Teku on the Jerimi-side of the Seru Francisco Jobo Field of Teku on the Jerimi-side of the Seru Francisco Jobo
- Flower of the Teku Flower of the Teku
- Far beneath us the large Palu di sia on the dam Far beneath us the large Palu di sia on the dam
- Orchids high in the tree Orchids high in the tree
- Large Iguana was surprised to see us Large Iguana was surprised to see us
- Circular pattern in a rock Circular pattern in a rock
- Cactus with usnea at the foot Cactus with usnea at the foot