Empress Deposit
Geologically within the Taseko property, there is an intensely altered, 177-to-223-metre-thick zone of volcanic rock sitting on relatively unaltered granitic rock north of a volcanic-granodiorite contact. In the Empress area, the contact between the granitic and volcanic rock, with the granitic rock to the south, dips steeply north and then plateaus at about 213 metres in depth. Copper-gold mineralization occurs within the altered volcanic rock. The three sub-zones within the Empress deposit are the 76, Upper North and Lower North zones (Vertical Section of Empress Zone). The highest grade mineralization of the three is in the Lower North zone, which ranges from 140 to 204 metres deep.
In 1990 and 1991, ASARCO Incorporated held an option on the property which has since expired. In 1991, ASARCO commissioned James Askew Associates, Inc. to conduct a pre-feasibility study on the Empress deposit. The parameters supplied by ASARCO for calculating the resource were:
In 1991, Giles R. Peatfield, PhD, P.Eng completed a pre NI 43-101 "mineral inventory" calculation for the Lower North Zone mineralization. His study showed a probable and possible inventory of 7,455,100 tons of 0.73% copper and 0.024 ounces per ton gold. This included a probable and possible core of 915,000 tons of 1.90% copper and 0.064 ounces per ton gold. The fact that high grade samples have been found on the surface (up to 7.14% copper) which are similar in mineralization to rock in the Lower North zone, indicates that there could be a zone similar in grade and mineralization to the Lower North Zone near the surface.
Both of the above mineral resource calculations are historical. As the studies predate NI 43-101, it must be declared that the potential quantity and grade is conceptual in nature; there has been insufficient exploration to define a mineral resource; and it is uncertain that further exploration will result in the target being delineated as a mineral resource.
In 1990 and 1991, ASARCO Incorporated held an option on the property which has since expired. In 1991, ASARCO commissioned James Askew Associates, Inc. to conduct a pre-feasibility study on the Empress deposit. The parameters supplied by ASARCO for calculating the resource were:
- Copper cut-off grade of 40%;
- Copper and gold recoveries of 90% and 80% respectively; and
- Metal format prices of $400 per ounce of gold and $1.00 per pound of copper.
In 1991, Giles R. Peatfield, PhD, P.Eng completed a pre NI 43-101 "mineral inventory" calculation for the Lower North Zone mineralization. His study showed a probable and possible inventory of 7,455,100 tons of 0.73% copper and 0.024 ounces per ton gold. This included a probable and possible core of 915,000 tons of 1.90% copper and 0.064 ounces per ton gold. The fact that high grade samples have been found on the surface (up to 7.14% copper) which are similar in mineralization to rock in the Lower North zone, indicates that there could be a zone similar in grade and mineralization to the Lower North Zone near the surface.
Both of the above mineral resource calculations are historical. As the studies predate NI 43-101, it must be declared that the potential quantity and grade is conceptual in nature; there has been insufficient exploration to define a mineral resource; and it is uncertain that further exploration will result in the target being delineated as a mineral resource.
