The 100% owned Rainbow Project is located approximately 7 hours by paved and gravel roads north of the city of Brasilia. The Rainbow Project exploration area covers approximately 30,000 hectares northwest of Minacu in the state of Goias in Brazil. The mining licenses are 805.597/77 and 860.691/89 each of 1000 hectares in size. About 2% of the total property on mining license 805.597/77 is subject to a royalty agreement that results in 10% of the ore recovered from the property being provided to the original garimpiero for his own processing. Read more
Alexandrites are unique in that they appear to change colour in different light. The stones are blue-green in daylight or fluorescent light, but appear a purple-red colour in incandescent light. The market target for the Rainbow Project alexandrites would be the large scale jewellery manufacturers and mass jewellery marketers. This market has never traditionally purchased, promoted or marketed alexandrite due to the lack of consistent supply and reliable sources. The Rainbow Project could address this inconsistency of supply. The small and medium sized retail jeweller would be a potential client as many of these jewellers are unable to obtain a consistent and reliable source for small polished alexandrites for their clients. The prices paid in small volume sales would be at least twice that paid by the mass merchandisers and wholesalers. For instance a single fine quality alexandrite of about 2.5 mm (0.08 ct.) with good clarity and colour would sell for about $500 per carat ($40 per piece ) whereas a mass merchandiser would pay no more than $150 per carat ($12 per piece) for volume purchases of the similar quality stones in parcels.
The Rainbow Project is a unique occurrence of alexandrite that occurs in a hard rock location. All other alexandrite occurrences in the world are related to alluvial deposits and secondary concentrations of unpredictable grade. The Rainbow Project is the only known alexandrite deposit in the world that has currently proven reserves of 50,300 tons with a value of $51.90 per ton worth a total of $2.61 million and probable reserves of 670,312 tons of undetermined value of higher grade alexandrite ore (this estimate is historical, does not use reserve and resource categories defined under National Instrument 43-101 and should not be relied upon).
The Rainbow Property was first exploited in the last decade for an occurrence of medium to low quality emeralds that was only marginally successful for the garimpieros. This area was known as the Pela Ema-Minacu emerald occurrence and was never of economic significance. Evidence of the previous workings may be found in the old adits and the old garimpos in the immediate vicinity of the current shaft adjacent to the Pelaema River. The emerald rich biotite schist is found at the base of the mineralized horizon and immediately above the footwall of foliated granites. Sample testing of these numerous old workings by Belo Sun (then Verena) resulted in the discovery of alexandrites associated with the emerald occurrences that were not previously recognized. Subsequently trenches were dug by Belo Sun (then Verena) and the sampling and mapping of these trenches confirmed the consistent occurrence of the marker horizons and alexandrite rich zones associated with biotite schists. Read more
In 1997 two new trenches were cut and sampled by the Company at the western end of the property to confirm the continuity of the mineralized horizon to the western extent of the property. It was observed that the weathered garnets in the marker horizons in Trench 400 were much larger than those observed in the older trenches, underground operations and other sample locations. This larger size of crystal formation is encouraging as it may result in a larger average size of alexandrite crystal formation.
Belo Sun has completed a 30 degree decline and a 40 meter shaft to the bottom of the mineralized horizon in the midst of the old workings beside the Pelaema River. The entire length of the decline and shaft has been carefully sampled and analyzed for emerald and alexandrite content and the detailed results are summarized below. After that two galleries were extended horizontally from the bottom of the decline to intersect the alexandrite rich biotite schists.
The alexandrite mineralization is always found associated with larger crystals of staurolite, kyanite, garnets, and chrysoberyl. The sizes of the blue kyanites, amber staurolite and reddish-brown garnet crystals were observed to be up to several centimeters in size whereas the size of the natural alexandrite crystals rarely exceeded 6-7 mm in size. In general the alexandrites are rare in the high grade zones of mineralization with the highest grade of rough alexandrite rarely exceeding 45 grams per ton (i.e.: 45 parts per million) in the surface trenches, underground decline, shaft and gallery sampling. In contrast the grade of the kyanite, staurolite and garnets have been visually estimated by Boyd to be about 5% by weight of the biotite schists (i.e.: 50,000 parts per million). During surface and underground sampling the associated kyanite, staurolite and garnets in conjunction with the biotite schist may be used as an indicator of an alexandrite mineralized horizon.
The Rainbow Project is located in metamorphosed and intruded Upper Precambrian sequences of the Araxa Group. Locally the host rocks are composed of biotite muscovite schists, quartz muscovite schists, quartzite and foliated granites in contact with the Serra Dourada granitic intrusive. The Serra Dourada Granite baltholith is the main geological feature that is directly related to the formation of the alexandrite and emerald occurrence on the Rainbow Project. The Serra Dourada Granite baltholith is exposed for a north-south distance of over 60 kilometers and between 10 to 20 kilometers wide in an east-west direction. A series of concentric and radial fractures generated by the intrusion of the Serra Dourada granites seem to be controlling factors in the formation of the gemstone mineralization. Read more
Immediately north of the current workings there is evidence of the old cassiterite (tin) mining operations that were exploited during periods of higher metal prices in the past but they are now abandoned.
The mineralized horizon that contains the emeralds and alexandrites is a consistent narrow horizon of about 28 meters thickness composed of metamorphic rocks of the Araxa Group. The horizon dips to the south and southeast at about 30 degrees. This horizon strikes in a roughly east-west direction for over 1000 meters across the property. The mineralized horizon is confined by quartz-muscovite schist in the hanging wall and by foliated granites and granites of the Serra Dourada batholith in the footwall. The mineralized horizon has a number of surprisingly consistent marker horizons that are found across the property.
These marker horizons are composed of garnet rich biotite schists. The marker horizons are interbedded with quartz biotite schists with disseminated alexandrite chrysoberyl, chrysoberyl, and garnet. Across the property it has been found that the alexandrite and emerald rich horizons occur at consistently predictable localities within the mineralized sequence and always associated with biotite rich horizons. The western portion of the mineralized horizon has been lost due to an interpreted fault and the eastern extension of the mineralized horizon continues off the property boundary onto ground controlled by another operation.
There are three areas of significant alexandrite mineralization in the mineralized horizon. They are referred to as the Lower Zone (LZ) immediately above the footwall contact with the foliated granites, the Middle Zone (MZ) which is about 10 meters above the footwall contact and finally the Upper Zone (UZ) which is about 10 meters below the hanging wall contact of the quartz muscovite schists with the mineralized horizon.
The only area of the Rainbow Project that has definable proven reserves is in the immediate area of the decline, shaft and underground galleries where detailed control sampling has been completed from the LZ, MZ, and UZ horizons in the mineralized section. On the surface, testing of the footwall contact has exposed the LZ horizon at the surface in the bed of the Pelaema River immediately beside the entrance to the decline. Alexandrite and emerald bearing biotite schist in the LZ horizon was noted and sampled at the surface but the shaft failed to encounter the LZ horizon near the footwall contact at the bottom of the shaft. The decline follows the UZ horizon as it dips at approximately 30 degrees down dip to near the area of the vertical shaft. Read more
The UZ horizon is about 2.58 meters thick, the MZ horizon is about 1.45 meters thick, and the LZ horizon is about 2.0 meter thick. Control sample cutting has been completed for alexandrites recovered from the UZ horizon but has not been completed on alexandrites recovered from the MZ and LZ horizons. The accessible extent of the proven reserves down dip is assumed to not exceed 100 meters and the strike extension of the proven reserves is assumed to be 20 meters on either side of the decline, shafts and galleries (i.e.: 40 meters).
There are a total of 50,300 tons of proven reserves and a total of 670,312 tons of probable reserves which is equal to 720,612 tons of proven and probable reserves (this estimate is historical, does not use reserve and resource categories defined under National Instrument 43-101 and should not be relied upon). These figures are based on the mining of the higher grade mineralized zones only and does not account for the substantial amounts of lower grade mineralization between the higher grade zones. As geological mapping and sampling of Trench 400 and Trench 500 is completed in the west zone the probable reserves may increase substantially as there are abundant indications of the continuity of the alexandrite mineralization in this area of the Rainbow Project.