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Thorium never occurs in geological concentration without other metals present. The Company is not aware of any instance where thorium occurs without other elements present in greater-than-background concentration. The chief mineral hosts for thorium are monazite, carbonatite, bastnaesite, thorite, thorianite, apatite and uranothorite, with the three main geological systems and their associated by-products being the following:
- Thorite, uranothorite and associated material most often appear as vein mineralization or other types of intrusive complexes. These types of materials are typically associated with medium-grade thorium, are nearly always underground, and are considered difficult to process metallurgically. In these systems, thorium can often be found with uranium.
- Carbonatite and bastnaesite are large underground volcanic systems associated with apatite, phosphate, and allanite material, and often contain niobium, tantalum, the lanthanide group of metals (also known as rare earth elements) and other base metals. As with the vein systems, these materials are also underground, requiring large underground mining operations, and may be difficult to process. Carbonatites are randomly distributed throughout the globe. There are significant carbonatitic systems reported in southern Africa, Brazil, Norway, Greenland, USA and elsewhere.
- Monazite is a lanthanide phosphate found in granites, syenites, pegmatites, quartz-pebble conglomerate sand stones, fluviatile and beach placers. In essence, the concentrations are accumulated at the shores of current or ancient oceans. These types of deposits are nearly always at surface, and are associated with titanium oxide materials, such as ilmenite, rutile and zircon, as they are in India, Australia, southern Africa and eastern USA. They can also be associated with tin, as they are in southeast Asia.
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