Uranium Division - Macusani
The Macusani district is the most studied area in southern Peru. IPEN historical reports from September 1983 refer to the areas of Chapi, Corani, Tantamaco, Huiquiza, Calvario, Concha Rumio, Huachanne, Chilcuno, Chacaconiza and the surrounding area to the town of Macusani potentially having in the order of 200,000 tons of Uranium carrying ore with average grades from 0.2% to 12% of U3O8 (Bulletin 71 – Peruvian Geological Society – September 1983)
The petrographic, mineralogical and tectonic characteristics of the uranium occurrences of Macusani, 150 kilometres to the north-northwest of Lake Titicaca in Puno, are such that these mineralizations are unique among Uranium deposits associated with pyroclastic rocks although similar to the mineralized systems in Lakeview (Oregon), McDermitt (Nevada), Marysvale (Utah), Makkovik (Labrador), Rexpar (BC), Mount Pleasant (New Brunswick) and Maureen (Quensland) in Australia.
The studies performed by IPEN showed that:
1. The Uranium ores are found principally at higher levels of the volcanic sequence;
2. The enclosing rocks are Plio-Quaternary rhyolitic and rhyodacitic ignimbrites formed by quartz, sanidine, oligoclase, biotite, and occasionally muscovite and andalusite, in a particular devitrified vitreous matrix containing numerous lutite clasts;
3. Biotite, smoky quartz and andalusite are very abundant in the mineralized levels;
4. The metallic ores consist almost exclusively of massive pitchblende more or less transformed into gummites, phosphates and silicates of uranium, and very sparse Fe sulphides;
5. The pitchblende fills fractures between a few centimetres and several metres long and between 1 and 100 millimetres wide. Some of these fractures are sub-vertical and are due to the contraction which gave rise to the columnar disjunction. Others are subhorizontal and parallel to a system of conjugate ductile shear formations produced by compaction and settling of the pyroclastic materials containing the mineralization.
Exploration of the Macusani area by 3rd parties has found significant outcrops of the uranium mineral autunite in small fractures in many areas. Autunite contains 51% uranium by weight and converts into 60% - 65% U3O8.
For drill results, click here