Summary
This report provides documentation of the Engebøfjellet eclogite and of the characteristics of garnet within it, including quantitative data on the chemical composition of the garnet, the amounts of garnet present and its grain-size distribution.
Based on image processing of thin-sections of rutile-ore-type eclogite, the garnet content generally varies from 25 to 40 wt.%, with an estimated average of 33 wt.%.
In representative rutile-ore-type eclogite the garnet grain-size is commonly in the range 100 to 250 microns (0.1-0.25 mm) and smaller, but larger garnet grains in the range 300-400 microns seem to occur fairly frequently.
Inclusions of other minerals in garnet are common, but the amounts of inclusions in representative "normal size" (less than 250 microns) garnet are generally regarded as low, although precise quantitative data is not available. In general, the amount of inclusions increases with garnet grain-size and may be considerable in the larger garnets.
Based on this information it is believed that high-quality garnet concentrates with garnet grain-size in the range 100 to 300 microns, could be produced from representative rutile-ore-type eclogite.
The documentation provided and the knowledge behind it represent highly relevant back-ground information for continued mineral processing trials in order to test the possibilities for making garnet concentrates of sufficient quality for various applications.
