Work in northern Yemen by Canadian Mountain Minerals (CYM-A) and Goldtex Resources (GXR-A) is proving to be a successful demonstration of the use of heavy-mineral concentrates to provide effective geochemical reconnaissance surveys over a large area.
Large it is, too: the partners hold a 41,588-sq.-km concession that covers most of northern Yemen. The Yemeni government had hired Toronto-based Watts, Griffis & McOuat to provide an initial survey of the geology and mineral potential of the area; WGM’s 1994 maps and reports were the inspiration for an exploration proposal that Canadian Mountain took to the Yemeni government in 1995. The company secured an exploration licence for the area and dealt Goldtex (which also owns 20.5% of Canadian Mountain) an option to earn 30% of the project.
The initial reconnaissance survey started in March 1996 with a drainage geochemistry survey. Samples from 3,755 locations in streams and dry streambeds revealed about 150 areas where heavy-mineral concentrates showed high metal content.
The partners were drawn to the Al Hariqah area, and followed up with detailed drainage geochemistry in a watershed tagged as anomalous in the regional survey. Geologists discovered a zone of shearing and sulphide mineralization in granites near their intrusive contact with metamorphosed sediments.
Trenching over the showing revealed mineralization over a strike length of 1.7 km, accompanied by a soil anomaly 25 to 125 metres wide over the mineralization. The crews also discovered a number of other shear zones, parallel to the original.
The shear zones are strongly silicified, with accompanying arsenopyrite and galena; surrounding the shears, the host rocks are pyritized. Near contacts with the country rock, there are some mineralized stockworks, and shallow-dipping, sheeted veins are also common.
Grab samples from the zone had widely varying gold grades, from non-detectable to 77.9 grams gold per tonne. More systematic chip samples showed concentrations from trace amounts of up to 15.2 grams gold per tonne, over widths that ranged from 1 to 6 metres, and one that ran 47.7 grams across 15 metres.
Grab samples from outcrops along strike to the north returned high gold grades as well, and visible gold was seen in outcrops along strike to the south. Armed with those results, the crews extended the grid over the showing southeastward, and mapped and sampled the strike extension of the shear.
The extended soil survey confirmed that the zone of high gold values in soil was at least 2.8 km long, apart from a 200-metre gap between its northern and southern portions; its widest point was about 150 metres across. The shear zone mineralization persisted along strike, its grade actually improving.
The most recent rock chip results show grades from trace levels of up to 55.2 grams gold per tonne. The zone grades 25.8 grams gold per tonne over its narrowest width, 0.5 metre; at its widest, 7 metres, it grades an average 18.7 grams per tonne.
The mineralization in the southeast is still most prominently developed in the granite, but at least one grab sample taken from a metamorphosed mafic volcanic rock graded 50.2 grams per tonne. The volcanic was veined with quartz and showed widespread carbonate alteration.
Canadian Mountain plans to delineate the mineralization at Al Hariqah with a drilling program, to begin in March.
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