Euhedral Chromite
Few years ago, we were a small team carrying out a regional geological mapping campaign in the South of New Caledonia. On the rocky ridges surrounding the ferricrete plateaus of the Prony Bay, we mapped dunite and harzburgite with varying degrees of serpentinization, as well as gabbros dykes.
Greenockite and artisanal mining
Somewhere in West Africa, while conducting reconnaissance on a remote site where a major gold rush took place in 2014, I found a sample that was unexpected in the context of the gold deposits in the sub-region.
At this site, while most of the artisanal miners focused on saprolite, some miners followed the mineralisation down to the bedrock, which consisted of very hard quartzite on the edge of a granitic intrusion. Artisanal mines in fresh rock are relatively rare given the challenges of digging at these depths; only very high grades could justify such work.
Cobalt in New Caledonia
In the early 2000s, during an exploration drilling program on the rim of the Goro deposit, our earthworks uncovered an old adit. It was dug by ‘cobaleurs’, those cobalt miners who were active in NC at the beginning of the 20th century. At that time, NC was almost the only world producer of this rare ore, then the discovery of the Copper Belt and its rich sulfides and oxides Co deposits will rapidly reduce New Caledonian production.
Cornetite from the Blue Mine, South Africa
During a field trip in South Africa, I visited the famous Blue Mine in Springbok. This old mine is part of the O’Okiep copper district located in the Namaqualand Metamorphic Complex.
The Blue Mine is historically significant as it is considered as the first ‘mining operation’ in South Africa. The mineralised outcrops have been mined by the native people of Namaqualand long before the arrival of European, but industrial mining started only in 1852 with this very mine.
The Mérétrice mine, New-Caledonia
The former lead-zinc-silver mine at Mérétrice was a small operation that was active intermittently between 1884 and 1930 in the far north of New Caledonia.
The Puech de Leguo quarry, Aveyron
This small quarry in north-western Aveyron has yielded a series of well-crystallised phosphates. Recent finds of saléeite and greifensteinite complete the list of rare minerals identified at this site. These discoveries are placed in the geological context of the La Capelle-Bleys leucogranite, which has long been prospected for various metals and then for uranium in […]