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Rimfire Portfolio - Thorn, BC

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High-sulphidation, copper-gold-silver epithermal vein system

The exploration target at the Thorn property is a large epithermal alteration system hosting massive pyrite-enargite-tetrahedrite veins.

In general, these deposits consist of a series of structurally-controlled pyrite-enargite-tetrahedrite veins that vary in width from a few centimetres to 20 metres wide. Alteration consists of strong clay and sericite often surrounding a zone of vuggy silica or strong alunite alteration. A well known example of this type of deposit is the El Indio Deposit in Chile. Production and reserves at El Indio total 23.2 million tonnes averaging 4% copper, 6.6 g/t (0.19 oz/ton) gold and 50 g/t (1.4 oz/ton) silver. El Indio also produced 191,000 tonnes of direct shipping ore that averaged 209 g/t (6.1 oz/ton) gold. Rimfire has no direct or indirect interest in the El Indio Deposit.

In 2002, another style of mineralization was identified at the Oban Breccia Zone. This zone is characterized by sericite-pyrite-ankerite altered heterolithic breccia with massive sulphides in the breccia matrix.

Strong clay-sericite altered (bright yellow and buff coloured) feldspar-quartz-biotite porphyry. Looking NE up Camp Creek.

The 2005 program at the Thorn culminated in drilling of Induced Polarization (IP) geophysical anomalies thought to represent parallel mineralized corridors similar to the Camp Creek Corridor, where the majority of the gold-silver-copper bearing vein mineralization has been found to date.

The Talisker Zone, one such target, had been intersected in drilling in 2004, confirming that coincident chargeability high/resistivity low anomalies can be used to target buried vein targets. A follow up hole in 2005 intersected 4.44 g/t gold, 407.9 g/t silver and 2.95% copper over 4.2 metres within a broad zone of 0.76 g/t gold, 48.9 g/t silver and 0.36% copper over 43.9 metres. The Talisker Zone remains open.

Other exploration highlights include very thick occurrences of silicified volcanic rocks in drill holes from the Cutty Sark Zone. This alteration includes <2% sulphide (pyrite with rare tetrahedrite-enargite). Further work is required to determine the significance of this alteration. Other targets, such as a high grade gold bearing baritic float found in a creek bed that assayed 265 g/t gold and 631 g/t silver. The source of this mineralization has yet to be found.

Exploration largely focussed on the gossans exposed in Camp Creek has identified numerous mineralized showings. Below is a summary of some of these occurrences:
• Oban Zone: New discovery in 2002. Prospecting to investigate an area of highly anomalous silver, arsenic and gold soil geochemistry identified in 2000, Rimfire crews found massive sulphide float boulders (15x15x15cm). One boulder assayed 6149 g/t (179 oz/ton) silver, 3.5 g/t gold, 40% lead, and 3.5% zinc.

  Oban Float - 6149 g/t (179 oz/ton) silver, 3.5 g/t gold, 40% lead and 3.5% zinc. Sample in photo is approximately 5 centimetres across. 27 KB, approx. 6 seconds at 56.6Kbps

• Catto Vein: Discovered in 2000, the recessive Catto Vein consists of massive pyrite, enargite and tetrahedrite in a fault paralleling the nearby contact between the porphyry and older andesites. A chip sample assayed 3.05% copper, 1.1 g/t gold and 132 g/t silver across a true width of 2.25 metres. The full width of this zone could not be determined due to overburden cover. The Catto Vein is in the same area where three cobbles collected in 1999 averaged 19.3% copper, 7.6 g/t gold and 1285 g/t silver.

  Two chip samples averaging 3.05% copper, 1.1 g/t gold and 132 g/t silver over a length of 2.25 metres. Full width of vein could not be determined due to overburden cover (left side of photo). 55 KB, approx. 11 seconds at 56.6Kbps

• Tamdhu Vein: Newly discovered in 2000, the Tamdhu Vein consists of chalcedonic quartz, pyrite, enargite and tetrahedrite; a chip sample assayed 1.26% copper, 4.2 g/t gold and 320 g/t silver across a true width of 2.1 metres. The vein has been traced for 30 metres on surface. A sample from a massive sulphide float boulder thought to be derived from the Tamdhu structure returned 12.05 % copper, 22.1 g/t gold and 2413 g/t silver. 2002 drilling intersected 1.65m of 3.65% Cu, 3.1 g/t Au and 454 g/t Ag.

• Glenlivet Vein: New discovery in 2002, the Glenlivet Vein extends for 220 metres from the western end of the F Zone. At its eastern end, a grab sample returned 2.97 g/t gold with 1298 g/t (38 oz/ton) silver and 12% copper. A 20 cm grab sample at the western end of the structure assayed 20.4 g/t (0.6 oz/ton) gold, 2580 g/t (75 oz/ton) silver and 23.9% copper.

• MP Vein: The MP Vein, which may form part of a wider system covered by boulders, is a 50 centimetre vein of massive pyrite and enargite exposed in Camp Creek. A grab sample across the vein (50 cm) contained 8.73% copper, 0.8 g/t gold and 224 g/t silver. A float boulder, in a side drainage 260 metres up Camp Creek, assayed 9.19% copper, 24.2 g/t gold and 1067 g/t silver.

• B Zone: The B Zone is a 30 metre wide zone of vuggy silica, chalcedonic veining and quartz breccia with relatively minor pyrite, enargite and tetrahedrite, which has been traced for about 300 metres along strike. Five 1986 drill holes tested the B Zone, with the best intersection grading 0.08% copper, 3.6 g/t gold and 44 g/t silver across 7.8 metres.

• F Zone: F Zone is a broad zone of intense alteration with quartz-sulphide veining that can be traced for 200 metres. A sample from this structure has returned 0.31% copper, 4.6 g/t gold and 389 g/t silver across 1.2 metres.

• I Zone: The I Zone comprises numerous parallel 10-70 centimetre quartz-pyrite-tetrahedrite veins in sericitized porphyry, across a true width estimated at 25-30 metres. A 70 centimetre quartz vein sample assayed 0.30% copper, 9.3 g/t gold and 760 g/t silver. Drilling in 2002 intersected 2.3m of 99 g/t (2.9 oz/ton) Ag and 3.5 g/t Au.

• G Zone: The G Zone is an argillite-hosted quartz-carbonate-sulphide vein, located a few hundred metres north of the porphyry contact. A 2.0 metre grab sample across the vein assayed 0.29% copper, 57.4 g/t gold and 90 g/t silver.

Breccia-hosted high-grade gold and silver mineralization

The Oban Breccia Zone was discovered in 2002 by field crews investigating the source of a very strong multi-element (silver-gold-arsenic-lead-antimony-zinc) soil geochemical anomaly. The discovery float boulder, located within the bounds of the anomalous geochemistry, assayed 6148 g/t (179 oz/t) silver, 3.5 g/t gold, 43% lead and 3.5% zinc. Further work in the area identified the outcrop source of the mineralization, and it was determined that it is hosted within a sericite-pyrite-ankerite altered heterolithic breccia. Mineralization consists of sulphides/sulphosalts (boulangerite-sphalerite-galena-pyrite) in the matrix between breccia clasts. High grade gold and silver mineralization was located over a 160 metre north-south trend. The southern-most outcrop (consisting of silicified breccia) yielded 25.9 g/t (0.75 oz/ton) gold and 391 g/t (11 oz/ton) silver from a grab sample.

The breccia is at least 300 metre diameter, and remains open to the south. The western portion of the breccia, host to some of the most anomalous soil geochemistry, is largely covered by overburden. Drilling has outlined a zone of silver-gold-lead-zinc mineralization within the breccia including 173.0 g/t silver, 1.2 g/t gold, 1.5% lead and 1.5% zinc over 25.2 metres.

Vein-hosted high-grade copper-gold-silver mineralization

The most common style of mineralization at the Thorn consists of copper-gold-silver mineralization dominantly hosted within, but not limited to, a strongly sericite and clay altered feldspar-quartz-biotite porphyry. Alteration occurs over an area of 1,400 by 2,000 metres. This alteration assemblage is consistent with that of high-sulphidation epithermal deposits throughout the world.

Previous workers had recognized the high grade copper-gold-silver veins at the Thorn as early as 1963. Impressive areas of strong clay and sericite alteration characterized by bright yellow, orange and buff-coloured rock exposed in creek canyons drew them into the area. Subsequently, numerous vein occurrences were identified and sampled. Since that time sporadic work was done on the property, culminating in an eight hole, 688 metre diamond drill program in 1986. Little work was done from 1986 until 1997 when Kohima Pacific Gold Corp. acquired the property. In early 2000, Rimfire obtained an option on the Thorn, and completed a work program that summer.

Rimfire geologists have identified three main types of mineralization within the altered porphyry, as well as one style that occurs in the surrounding sediments and volcanics.

Vein Mineralization Within the altered porphyry:

1. High-grade copper-gold-silver bearing massive pyrite, enargite and tetrahedrite veins. Examples of this type of veining include the Tamdhu and Catto veins and float boulders found in the vicinity of these veins. The Catto Vein assayed 3.05% copper, 1.1 g/t gold and 132 g/t silver over a true width of the 2.25 metres exposed in a chip sample (full width could not be determined due to overburden cover). Float boulders collected from the area averaged 19.3% copper, 7.6 g/t gold and 1285 g/t silver from three samples in 1999.

   Massive pyrite-enargite-tetrahedrite boulder from Tamdhu showing area - 12.05 % copper, 22.1 g/t gold and 2413 g/t silver

2. High-grade gold-silver mineralization hosted in quartz veins and breccias with pyrite and minor enargite and tetrahedrite. Mineralization at the B and F Zones are examples of this mineralization style. One 1986 drillhole, testing B Zone mineralization, intersected 7.8 metres of 0.08% Cu, 3.6 g/t gold, and 44 g/t silver.

3. High-grade gold-silver in quartz-pyrite-tetrahedrite sheeted veins. Zone I consists of numerous 10-70 centimetre quartz-pyrite-tetrahedrite veins across a true width of approximately 25-30 metres. Samples of this mineralization returned 0.7 metres of 0.3% copper, 9.3 g/t gold and 760 g/t silver. Drilling of this target 2002 intersected 2.3 metres of 99 g/t (2.9 oz/ton) Ag and 3.5 g/t Au within a 7-metre fault in hole THN02-09 . Hole THN02-10 cut 1.50 metres of 70.7 g/t (2.1 oz/ton) Ag and 1.4 g/t Au within the same zone.

Mineralization hosted within volcanic/ sediment package:

1. High-grade gold-silver hosted in quartz-carbonate-sulphide veins. Zone G, located a few hundred metres north of the porphyry contact exemplifies this style, with a 2.0 metre grab sample assaying 0.29% copper, 57.4 g/t gold, and 90 g/t silver.

The Thorn property consists of 172 sq. km of contiguous claims. Rimfire Minerals owns 100% of the project. A 3.5% Net Smelter Return (NSR) is payable to underlying vendors at commercial production. The Joint Venture can purchase 2% of the NSR for $3 million.