The Iron Mask batholith lies in the southern part of the Quesnel trough, also known as the Nicola belt. The most important pre- Tertiary rocks in this belt are Upper Triassic volcanic and sedimentary rocks of the Nicola Group. The batholith is a subvolcanic, multiple intrusion which is comagmatic and coeval with the Nicola rocks. It is situated along the southwest side of a regional northwest trending fracture zone and is itself cut by numerous northwesterly faults. The batholith comprises two major northwest trending plutons separated by 6 kilometres of Eocene Kamloops Group volcanic and sedimentary rocks. The Tertiary rocks occupy what appears to be a graben structure resulting from renewed fault movement around the margins of the plutons during Paleocene or Early Eocene time (Bulletin 77). The larger pluton, the 18 kilometre long southern part of the batholith, is called the Iron Mask pluton. The smaller Cherry Creek pluton farther northwest, outcrops on either side of Kamloops Lake. The combined exposure of the batholith, including the intervening younger rocks, is about 33 kilometres long and 5 kilometres wide.

Sedimentary and volcanic rocks of the Kamloops Group unconformably overlie the Nicola rocks and the Iron Mask batholith. These include tuffaceous sandstone, siltstone and shale with minor conglomerate, as well as basaltic to andesitic flows and agglomerates with minor dacite, latite and trachyte.

In the vicinity of the batholith, the Nicola Group is dominated by volcanic and volcaniclastic sedimentary rocks. They are generally recognized by albitization of feldspars, occurrence of patchy epidote, and/or rare hematite alteration. On the southwestern flank of the Iron Mask pluton, well-indurated, massive and bedded tuff, breccia and interbedded flows and flow breccia are prominent and are weakly metamorphosed. On the northeast flank, less well-indurated and less altered tuff and tuff breccia predominate. However, adjacent to the intrusive contact, these rocks are also well indurated and epidotized and are locally mineralized with sulphides. At the southeastern tip of the Iron Mask pluton and locally along the southwestern flank, the Nicola rocks comprise distinctive porphyritic augite-hornblende basalt.

The Iron Mask pluton comprises four major, successively emplaced units designated as the Iron Mask Hybrid, Pothook, Sugarloaf and Cherry Creek units. Locally, an additional Picrite unit also occurs which is probably not genetically related to the batholith. The smaller Cherry Creek pluton consists entirely of the Cherry Creek unit. Isotopic dates (194 to 204 Ma +/- 6 Ma) indicate that all of these units are of Late Triassic or earliest Jurassic age (Bulletin 77).

The component units (except the Picrite unit) of the multiphase batholith are largely controlled by major systems of northwesterly, northerly and northeasterly trending fractures or faults. Most units show some degree of alteration and/or contamination which may be intense locally. Weak to moderate saussuritization is ubiquitous in all batholithic rocks while potassium feldspathization is more prominent in rocks of the Cherry Creek unit. The units are briefly described in order of oldest to youngest (determined mainly on crosscutting relationships).

The Iron Mask Hybrid unit forms the spine of the Iron Mask pluton. It is mostly agmatitic, consisting of rounded to angular fragments of various sizes, texture and composition in a dioritic matrix. The fragments include mainly coarse and fine-grained diorite and coarse-grained gabbro with lesser amounts of medium to coarse-grained hornblendite and scattered xenoliths of Nicola Group volcanic rocks. All rock varieties in the unit contain magnetite which is often more than 10 per cent by volume. Mineralization, particularly of iron and copper, is almost ubiquitous in this unit. The Iron Mask mine (092INE010), a former copper producer, is located in this unit, but is also associated with picrite.

The Pothook unit occurs mainly in the northwestern half of the Iron Mask pluton, appearing frequently as narrow, gradational zones between the Iron Mask Hybrid and Cherry Creek units. Rocks of this unit are uniformly of dioritic composition and are medium to coarse grained. The Pothook unit is locally mineralized with copper and iron.

The Picrite unit consists of rocks of basaltic composition with abundant clinopyroxene and serpentinized olivine phenocrysts. These rocks generally occur as steeply dipping, poorly exposed and relatively small lenticular bodies in many parts of the batholith. They appear to be associated with recurring, northwesterly trending fracture systems and copper mineralization frequently occurs in their vicinity. Because picrite basalt has been observed far from the two component plutons of the batholith, it is probable that this unit is not part of the batholith.

The Sugarloaf unit occurs mainly along the southwest side of the Iron Mask pluton and as small enclosed bodies in the southern half of the pluton. Rocks of this unit are mainly porphyritic with hornblende, minor clinopyroxene and plagioclase in a greyish green matrix. They are of fairly uniform diorite-andesite composition. Several copper occurrences are hosted by the Sugarloaf rocks. The Ajax deposit (092INE012) (West and East zones) east of Jacko Lake is located within brecciated and albitized Sugarloaf rocks.

The Cherry Creek unit is the most widely distributed phase of the batholith. It constitutes the entire Cherry Creek pluton. The unit consists of rocks with composition ranges from diorite, monzonite, syenite to their porphyritic and fine-grained equivalents as well as local intrusive breccias. Copper and minor iron mineralization is prominent in the Cherry Creek unit, particularly in zones of intense brecciation associated with alkali metasomatism. Afton mine (092INE023) lies at the western termination of a narrow, 4 kilometre long, easterly trending zone of intense intrusive brecciation that is located at the northern edge of the Iron Mask pluton.

The Rainbow deposit is on the southwest margin of the Iron Mask batholith. It is located on the eastern slopes of Sugarloaf Hill which is predominantly underlain by porphyritic hornblende diorite of the Sugarloaf unit. These rocks are bounded to the west and south by Nicola Group volcanics. The property is cut by a strong northwest trending fault (Sugarloaf fault) and also crosscutting northeast trending faults. The Sugarloaf fault appears to be an important feature as the bulk of the known copper mineralization occurs near it or within tectonic breccias which may be related to it. Local dyke-like bodies of the Picrite unit are also observed in this area.

Mineralization is predominantly pyrite and chalcopyrite as disseminations and stockworks in breccia zones. Indicated reserves of the Rainbow are 4,467,000 tonnes grading 0.663 per cent copper, 137.1 grams per tonne silver and 0.008 per cent molybdenum (Seadrift International Exploration Ltd. Amalgamation Brochure, November 16, 1988).

In 1994, Teck Exploration and Getchell Resources Inc. carried out an integrated exploration program on the Rainbow claims. Thirty-one diamond-drill holes were completed totalling 5959 metres. Results were mineralized intersections obtained from the Number 1 zone are typically less than one-half the grades and thicknesses for similar intersections historically reported on this zone. The potential of the Number 1 zone to form a significant mineralized occurrence has been downgraded by this drill program (Assessment Report 23917). A new and significant mineralized zone, the 17 zone, was discovered during the 1994 drill program. Mineralization in this zone is hosted by an extensively potassically altered hornblende diorite. The rock has also been altered by early stage andradite. The mineralized intrusion is strongly overprinted by late stage carbonate and iron carbonate alteration. Copper grades within the intrusion are strong, ranging from 0.25 per cent copper to well over 1.0 per cent copper. Gold contents are weak and are typically less than 0.2 gram per tonne gold. The zone has a strike length of greater than 200 metres, a maximum width of 100 metres and is open at depth. The updip continuity of mineralization in the 17 zone is truncated by two processes. These are: a) the zone has been offset 80-100 metres, east-side down, across a significant extension fault. This fault is known locally as the Leemac, or Sugarloaf Fault. Dextral rotation across this fault may predate east-side down extension; b) a flat intrusive contact exists between mineralized hornblende diorites and the overlying non-mineralized Pothook and Hybrid diorite rocks. The contact appears to be an intrusive contact between the two intrusions. It is not a tectonic contact.

Drilling in 1996 tested a new zone of copper and gold mineralization. Teck drilled 6 deep holes in 1997. A 159-metre intercept graded 1.078 per cent copper and 0.322 grams per tonne gold. While the breccia unit is impressively mineralized, the geometry and grade distribution of the mineralization would not support mining. The zone is still open below 400 metres. Teck Corporation has completed a study of three dimensional modelling of a 104 diamond-drill hole database which resulted in an in situ geological resouce of 15,860,000 tonnes grading 0.528 per cent copper using a 0.25 per cent copper cutoff (George Cross News Letter No. 160, August 20, 1997).

In January 2002, Abacus Mining and Exploration Corporation obtained the Rainbow property and in April released new assays for part of a 1995 Teck drillhole. A 57.0 metre interval graded 1.06 per cent copper, 0.27 gram per tonne gold and 1.04 grams per tonne palladium. Abacus completed a ten hole, 3300 metre drill program in June 2002. The program was designed to test the Number 2, 22 and 17 zones. Drillhole R-02-006 intersected 299.2 metres grading 0.81 per cent copper, 0.25 gram per tonne gold and 0.05 gram per tonne palladium in the Number 2 zone. Higher grade areas in this zone include 30.5 metres grading 2.17 per cent copper, 0.55 gram per tonne gold and 0.07 gram per tonne palladium, as intersected in drillhole R-02-009 (Press Release July 10, 2002). Drillhole R-02-001 intersected 37.5 metres grading 0.51 per cent copper in the Number 17 zone. Drillhole R-02-08 tested the Number 22 zone and intersected 31.1 metres grading 1.12 per cent copper, 0.45 gram per tonne gold, 0.94 gram per tonne palladium and 0.02 gram per tonne platinum.

The Rainbow property is located on the east flank of Sugarloaf Hill, about 10 kilometres southwest of Kamloops. The Chieftain Group, comprising the Chieftain, Chieftain No. 2 and Northern claims, was located in 1896 by R.H. Lee. The nearby Lone Tree (Lot 883) and Green Cub claims were located at a later date. The Lone Tree claim was Crown granted to Mr. Lee in 1903. The initial exploration work, begun in 1896, included two 15-metre shafts and an adit. The Chieftain Copper Mines of British Columbia, Limited, was incorporated in September 1901 by Detroit interests to acquire the property. Very little exploration work was reported; the company charter was surrendered in 1912. No further activity was reported until 1961 when Huestis Mining Corporation Ltd. optioned 23 claims from Mr. H. Messmar, of Kamloops. Work by the company included bulldozer stripping and diamond drilling in 4 holes. The option was subsequently dropped. Western Beaver Lodge Mines Ltd. during 1965 held a number of claims in the Rainbow, Lee, 10, RO, and Rob groups, and the Lone Tree Crown grant. Geophysical work was reported at that time. Vanco Explorations Limited is reported to have held the ground in 1966 and to have carried out limited geophysical and geochemical surveys, and diamond drilling in 2 holes. Belcarra Explorations Ltd. held the property in 1969. A geochemical survey, bulldozer trenching and 106.6 metres of diamond drilling in 5 holes was reported.

Leemac Mines Ltd. in 1971 optioned the Rainbow and Lee groups (31 claims), and Mineral Lease 23K (Lot 883) from the Messmar interests and R.J. Hickey, all of Kamloops. Exploration work during the latter part of the year included the rehabilitation of the grid lines used in the magnetometer and induced polarization surveys by Western Beaver Lodge Mines; this work had indicated a circular shaped series of 4 anomalous highs. Other work by Leemac in 1971 included trenching, a geochemical survey south of Sugarloaf Hill, 305 metres of Winkie diamond drilling, and 609.6 metres of percussion drilling. Wireline diamond drilling was begun on Zone No. 1 in December and 11 holes totalling 1604.7 metres were completed.

Western Mines Limited, by an option agreement of March 1972, purchased 100,000 treasury shares with the option of further participation. Drilling continued in Zone 1 and was expanded to Zone 2 in May. Some 31 holes totalling about 5486.4 metres were completed to mid-June. Western Mines decided not to purchase further shares and the agreement terminated in July 1972. Leemac continued the drilling program and to April 1973 had partially outlined a mineralized breccia zone (Zone 2) containing an indicated 14,172,711 tonnes with a weighted average grade of 0.54 per cent copper (Chisholm, E.O., May 21, 1973 in Leemac Mines Ltd. Statement of Material Facts, June 4, 1973). Leemac in July 1973 optioned the property to Getty Mining Pacific, Limited; Getty at that time held an option agreement on four adjacent properties. Work on the Rainbow property in 1973 included geological mapping, an induced polarization survey over 6.1 line kilometres, a magnetometer survey over 28.9 line kilometres, 890.6 metres of rotary drilling in 5 holes on Rainbow 5, 6 and D Fr., and 4992.6 metres of percussion drilling in 47 holes. Further diamond drilling was done in 1974 in one hole to a depth of 313.3 metres on Rainbow 17 claim. Getty abandoned the option in the latter half of 1974. Nahatlatch Resources Ltd. in December 1975 optioned a 65 per cent interest in 51 claims and one mineral lease from Leemac Mines Ltd.; the company name (Leemac) was changed in April 1976 to LMC Resources Ltd. Work by Nahatlatch during 1976 included diamond drilling in 23 holes averaging 300 metres in depth. Under the terms of the option agreement the property was then owned by Nahatlatch (65 per cent) and LMC Resources (35 per cent). No. 2 zone reserves were reported as 13,311,692 tonnes indicated averaging 0.59 per cent copper, and 11,737,874 tonnes inferred of an expected comparable grade, to a depth of 304.8 metres. Included is a higher grade section of 3,902,344 tonnes averaging 1.05 per cent copper (Northern Miner, December 9, 1976). Further diamond drilling was carried out in the first part of 1977.

By 1977, the property had been restaked as four claims, the Rainbow NE, SE, SW, NW (26 units). Canadian Superior Exploration Limited optioned this ground in June 1977; the company also held an option on the adjacent Victor, Iron Mask, Iron Cap and DM properties (092INE010, 18, 30). Work on the Rainbow ground included 9 percussion-drill holes totalling 570 metres and 375 metres of diamond drilling in 2 holes; the option was terminated in the fall of 1977. Seadrift Resources Ltd. was formed in November 1978 by the amalgamation of Nahatlatch Resources and LMC Resources. The company name was changed in August 1980 to Pacific Seadrift Resources Ltd. In 1979, diamond drilling in 10 holes totalling 3070 metres was done on Rainbow SE. Late in 1979 the company purchased the adjacent Kam, Roda, Roda 2 and Red Head claims (15 units) from Sovereign Metals Corp; geophysical surveys and drilling had been carried out on these claims by Sovereign in 1976 and Canadian Superior Exploration in 1977. Pacific Seadrift in 1980 spent $155,000 as part of the cost of drilling 10 holes on its property. E & B Canada Resources Ltd. contributed $1 million to exploration costs in 1980-81 for a 6 per cent interest in the combined Rainbow, Victor, Iron Mask, Iron Cap and DM properties. Based on work to date, drill indicated reserves were estimated at 95,245,500 tonnes grading 0.32 per cent copper and 0.27 gram per tonne gold (Joint Management Information Circular, Royex Sturgex Mining and Cullaton Lake GML, (27/041/84)). Craigmont Mines Limited in February 1981 optioned the above combined properties and diamond drilled 5579 metres in 34 holes on the Rainbow and Victor. This work indicated insufficient tonnage to support an independent mining operation; the option was given up in September 1981. The company name (Pacific Seadrift) was changed in 1985 to Seadrift International Exploration Ltd.

In 1987, Seadrift International Exploration Ltd. (Seadrift International) , the successor company to Pacific International explored the northeastern portion of the Rainbow claims with induced polarization, magnetic and VLF electromagnetic surveys. Several anomalies were outlined and in 1988, five diamond holes totaling 679 metres tested two of the anomalies. Results were not encouraging.

In 1990, Getchell Resources Inc. (Getchell) optioned the property from Deak Resources Corp. (Deak) who by then were in control of the Rainbow claims. In 1993, an induced polarization survey was done over an area southeast of the No. 1 zone where a data review indicated mineralization might be near surface. A chargeability anomaly was detected southeast of the No. 1 zone.

Teck subsequently acquired a 70 per cent interest in the Rainbow claims from Getchell later in 1993 and began an aggressive exploration program in 1994, in an attempt to find easily accessible ore to feed the Afton mill. In addition, geochemical and ground induced polarization surveys on the No. 1 and No. 2 zones were completed and drilling began in the No. 1 zone area. In 1994, thirty-one diamond drill holes totaling 5966 metres were completed in and around the No. 1 zone and ultimately led to the discovery of the No. 17 zone. However, Teck concluded that the mineralization was too deep for easy extraction and no further work was done.

In 1995, Teck focused on the No. 2 zone in an attempt to expand on the known reserves and to test for the mineralization extending to surface. Twenty-seven diamond drill holes were completed totaling 5985.3 metres. The 1995 drilling was carried out in the area of the historic drilled area and helped to better define the grade and geometry of the zone. Of the few holes drilled off the zone, Hole 95-22 was successful in intersecting significant mineralization in what is now called the No. 22 zone, which lies southeast of the No. 2 zone. Teck continued to drill the No. 2 zone in 1996 with an additional 13 holes totaling 1980.9 metres. Much of this drilling was done along the south boundary of the No. 2 zone with some holes stepped southeast towards the No. 17 zone. Results of this program were generally poor, with some narrow scattered intersections. In 1997, six holes were drilled in the No. 2 zone to define the limits of the higher grade breccia core. The results were considered good.

Excluding some shallow, pre 1971 Winkie drill holes and the occasional scattered diamond drill hole in the 1960s, it has been calculated there has been a grand total of 54,399 metres of drilling on all zones in the Rainbow property.

Abacus Mining and Exploration Corp. optioned seven Afton Area properties in the Iron Mask batholith from Teck Cominco Ltd. The properties include the Rainbow, Crescent and DM-Audra alkalic porphyry Cu-Au occurrences, along with the recently closed AjaxWest and Ajax East pits. In 2002, Abacus compiled and reviewed the voluminous dataset for the properties, and drilled 3276.8 metres in 10 holes on the Rainbow property. Hole R-02-006 cut 299.2 m grading 0.25 grams per tonne gold, 0.81 per cent copper and 0.05 grams per tonne palladium (Exploration and Mining in BC 2002, 47).

In 2003, Abacus again focused their interest on the Rainbow property. The company completed a large 3-D IP and magnetic survey, and drilled 1865 metres in four deep holes on the Rainbow #2 copper-gold zone. The 2003 holes are reported to have hit only narrow intervals of high-grade mineralization at depth.

In 2004, Abacus Mining conducted a very aggressive exploration program on their large Afton area property. Work included a large 3-D induced polarization survey and more than 27 000 metres of drilling, split between the Rainbow deposit, the DM-Audra-Crescent area (092INE030 and 026), and the Coquihalla zone. The 2004 drilling attempted to extend the higher grade mineralization in the Rainbow #2 and #22 zones to depth.

In 2005, Abacus turned its focus to the past-producing Ajax pits and there is no report of work done on the Rainbow. It was reported in 2005 that the Rainbow hosts an indicated resource of 100.6 million tonnes grading 0.237 per cent copper and 0.066 gram gold per tonne, using a cutoff grade of 0.1 per cent copper. If the cutoff grade is raised to 0.35 per cent copper, the indicated resource drops to 14.8 million tonnes of 0.53 per cent copper and 0.119 gram gold (Northern Miner July 7, 2005).